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__ __ _
___\ \/ /_ __ __ _| |_
/ _ \\ /| '_ \ / _` | __|
| __// \| |_) | (_| | |_
\___/_/\_\ .__/ \__,_|\__|
|_| XML parser
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!! <blink>Expat has UNFIXED SECURITY ISSUES!</blink> !!
!! Please see https://github.com/libexpat/libexpat/issues/1160 for details. !!
!! !!
!! Starting 2026-08-01, for up to six months my work maintaining libexpat !!
!! will be funded by the City of Munich as part of their !!
!! Open Source Sabbatical (https://opensource.muenchen.de/sabbatical.html) !!
!! — thank you! !!
!! !!
!! If your business relies on Expat beyond January 2027, please consider !!
!! funding the maintenance of Expat to ensure its health and security for !!
!! you and others. Thank you! !!
!! !!
!! Sebastian Pipping -- Berlin, 2026-09-22 !!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Release 2.8.5 Tue September 22 2026
Security fixes:
#1282 CVE-2026-93990 -- Reject high surrogates not followed by a
low surrogate during UTF-16 decoding; previously, malformed
UTF-16 could be smuggled into the application using Expat
and could cause arbitrary damage there, depending on how
malformed UTF-16 was handled inside the application;
validation was not their job but Expat's. This is similar
to past vulnerability CVE-2022-25235.
Upstream CVSS 3.1 vector:
AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H (CVSS score: 9.8)
///////////////////////////////////////////////////////////////////////////////
// The next release will drop two (disabled-by-default) features: //
// //
// - ATTR_INFO (-DXML_ATTR_INFO, -DEXPAT_ATTR_INFO, --enable-xml-attr-info, //
// function XML_GetAttributeInfo, struct XML_AttrInfo) //
// - MIN_SIZE (-DXML_MIN_SIZE, -DEXPAT_MIN_SIZE) //
// //
// If you need them in 2026 and beyond, please share your scenario at //
// GitHub issues #1370 (for ATTR_INFO) and/or #1379 (for MIN_SIZE). Thanks! //
///////////////////////////////////////////////////////////////////////////////
Bug fixes:
#1346 lib: Fix OOM-related memory leak on a failed overflow check
#1371 lib: Fix memory alignment for architectures with 128bit
pointers like CHERI-RISC-V
#1367 xmlwf: Handle errors when closing output files
Other changes:
#1354 lib: Reject an XML declaration version other than `1.[0-9]+`
(which is less strict than XML 1.0r4 (fourth edition)
and matches XML 1.0r5 (fifth edition))
#1362 lib: Make Clang, GCC and MSVC warn about use of function
XML_SetHashSalt that is deprecated since Expat 2.8.0
#1357 lib: Drop internal macros FASTCALL, PTRCALL, PTRFASTCALL
#1367 xmlwf: Document that with `-k` the last error determines the
xmlwf exit code in `--help` output
#1367 xmlwf: Make exit code 3 documentation match exit code 2 more
closely in `--help` output
#1352 #1353 CMake|Windows: Refrain from adding `/source-charset:utf-8`
for MSVC
#1366 #1374 Autotools: Be explicit about the minimum required version of
GNU Automake, currently version 1.13 of 2012-12-28
#1351 Autotools|macOS: Sync CMake templates with CMake 4.4.3
#1349 Replace some internal use of XML_Bool with standard bool
#1364 tests: Propagate xmltest.sh failures via exit status
#1360 tests|xmlwf: Add `#include "expat_config.h"` where missing
#1355 tests: Start covering hash table operation
#1350 #1369 tests: Drop __cplusplus leftovers
#1378 tests: Fix tail pointer when unlinking the last tracked
allocation
#1376 docs: Emphasize that XML_StopParser is not immediate
#1381 docs: Sync XML_FeatureEnum value list in doc/reference.html
#1356 #1361 Version info bumped from 13:4:12 (libexpat*.so.1.12.4)
to 13:5:12 (libexpat*.so.1.12.5); see https://verbump.de/
for what these numbers do
Infrastructure:
#1347 Add missing .gitignore entries
#1360 CI: Detect missing `#include "expat_config.h"`
#1368 CI: Bump MinGW Clang from 23.0.1 to 23.1.1
#1377 CI: Bump Fil-C from 0.684 to 0.685
#1380 CI: Bump Cppcheck from 2.21.0 to 2.22.0
#1372 CI: Extract helper script `apply-htmltidy.sh`
#1366 #1374 Autotools: Start to also produce .tar.bz3 release tarballs
Special thanks to:
Afonso Januário
Braian Plaku
Florian Schmaus
Huang Wenbin
Kamila Szewczyk
Kartik Kenchi
Leo Camus
Matthew Fernandez
Stan Ulbrych
and
City of Munich Open Source Sabbatical
Release 2.8.4 Mon August 31 2026
Security fixes:
#1321 #1331 CVE-2026-66046, CVE-2026-76641 -- Fix quadratic runtime from
"attribute isCdata lookups" that allowed denial of service
attacks through moderately sized crafted XML input
(CWE-407).
The vulnerability is closely related to past CVE-2026-45186
that was fixed with Expat 2.8.1.
Please note that a layer of compression around XML can
significantly reduce the minimum attack payload size.
Upstream CVSS 3.1 vector:
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (CVSS score: 7.5)
(Note the "AV:N" for network/remote.)
#1322 CVE-2026-76957 -- Protect custom encoding callbacks from
parser re-entry. The vulnerability is closely related to
past issues CVE-2026-50219, CVE-2026-56131 and
CVE-2026-56412 that were all fixed with Expat 2.8.2.
#1326 CVE-2026-76956 -- Fix inverted getentropy() return handling
Allows for hash flooding denial of services in
configurations where getentropy is configured or detected
as the only high quality entropy extractor.
Upstream CVSS 3.1 vector:
AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H (CVSS score: 5.9)
(Note the "AV:N" for network/remote.)
Other changes:
#1332 #1333 CMake: Only add `/source-charset:utf-8` when `/utf-8` is not
present
#1315 lib: Resolve (currently unreachable) undefined behavior from
overshifting a signed int to the left
#1325 #1334 lib: Support read-only hash table lookup with keys that are
not zero-terminated
#1340 lib: Use a C99 bool for `ENTITY.open`
#1319 Fix typo in comment
#1320 Sync file headers
#1328 #1329 Version info bumped from 13:3:12 (libexpat*.so.1.12.3)
to 13:4:12 (libexpat*.so.1.12.4); see https://verbump.de/
for what these numbers do
Infrastructure:
#1317 #1335 CI: Cover compilation and execution with Fil-C
#1337 CI: Cover compilation and execution on riscv64
#1338 CI: Cover compilation and execution with Clang-based MinGW
#1339 CI: Cover compilation and execution on (big-endian) s390x
#1316 CI: Run test suite with musl, also
#1336 CI: Bump WASI SDK from 33 to 34
#1345 CI: Bump Clang from 22 to 23
Special thanks to:
Alberto Maschietto
Alexander Bluhm
Berkay Eren Ürün
Darren Carreras
Fabian Wahle (Hap Security)
Matteo Forzan
Matthew Fernandez
Sorrashut Kaewtaworn
Wade Sparks III
Zeyou Liu
and
City of Munich Open Source Sabbatical
Moonshot AI
VulnCheck
Z.ai
Release 2.8.3 Mon August 10 2026
Security fixes:
#1296 CVE-2026-72522 -- Fix an out-of-bounds read and the resulting
infinite loop caused by treating low surrogates (Unicode)
the same as high surrogates in functions *_toUtf16.
Needs Expat compiled with 16bit character support
(e.g. with Firefox and/or on Windows) to be affected.
Upstream CVSS 3.1 vector:
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (CVSS score: 7.5)
(Note the "AV:N" for network/remote, the "AV:L" in NVD by
Mitre is mistaken.)
Original bug report from Mozilla at:
https://bugzilla.mozilla.org/show_bug.cgi?id=2053153
Bug fixes:
#1297 #1300 lib: Fix support for 2+ GiB documents (regression from 2.8.2)
#1286 lib: Reject empty version in the XML declaration
#1305 #1306 lib: Fix printf format for AIX
Other changes:
#1309 CMake|AIX: Enable EXPAT_DEV_URANDOM by default for AIX
#1295 CMake|Windows: Add a 64bit MinGW toolchain file
#1287 #1289 CMake|Windows: Start invoking MSVC with /source-charset:utf-8
#1289 CMake|Windows: Start requiring MSVC 2015 Update 2 or later
#1300 Document the current wrap-around issues with functions
- XML_GetCurrentByteIndex
- XML_GetCurrentColumnNumber
- XML_GetCurrentLineNumber
- XML_GetAttributeInfo
explicitly.
#1303 Address Clang Static Analyzer 22 warning
`core.NullPointerArithm`
#1313 #1314 Version info bumped from 13:2:12 (libexpat*.so.1.12.2)
to 13:3:12 (libexpat*.so.1.12.3); see https://verbump.de/
for what these numbers do
Infrastructure:
#1311 CI: Limit workflow runtime and package installation runtime
#1310 CI: Pin Cppcheck version for a robust CI
#1310 CI: Migrate Cppcheck CI from macOS to Linux
#1312 CI: Get CFLAGS and CXXFLAGS back in sync for both Emscripten
and WASI SDK
#1304 CI: Activate AddressSanitizer for MSVC Windows CI
#1308 CI: Introduce zizmor static analysis for GitHub Actions
#1308 CI: Start using `persist-credentials: false` with Git checkout
#1219 CI: Add a 7 day cooldown to Dependabot for GitHub Actions
#1302 #1303 CI: Bump Clang from 21 to 22
#1293 #1294 Update project status for 2026-08
#1301 #1307 Add SPDX license identifiers to the source code
Special thanks to:
Evgeny Kotkov
Henri Sivonen
Kartik Kenchi
Matthew Fernandez
Matthew Wozniczka
Stan Ulbrych
Tuukka Pasanen
William Woodruff
and
Anthropic
City of Munich Open Source Sabbatical
Mozilla Security Team
Subversion
zizmor static analysis
Release 2.8.2 Thu June 25 2026
Security fixes:
#1246 CVE-2026-50219 -- Disallow calls to functions
`XML_GetBuffer`, `XML_Parse`, `XML_ParseBuffer`,
`XML_ParserFree`, `XML_ParserReset` to guard e.g.
Expat bindings from memory corruption;
this CPython issue is related:
https://github.com/python/cpython/issues/146169
#1267 CVE-2026-56131 -- Protect XML_ResumeParser from being called
from a handler, plugging a hole in the fix
to CVE-2026-50219
#1272 CVE-2026-56132 -- Fix out-of-bound scaffolding index store
in `doProlog`
#1229 #1232 CVE-2026-56403 -- Integer overflow in `storeAtts`
#1249 CVE-2026-56404 -- Integer overflow in `addBinding`
#1251 CVE-2026-56405 -- Integer overflow in `getAttributeId`
#1255 CVE-2026-56406 -- Integer overflow in `XML_ParseBuffer`
#1262 CVE-2026-56407 -- Integer overflow in `textLen` handling
#565 CVE-2026-56408 -- Integer overflow in `copyString`
(commit 16e2efd867ea8567ffa012210b52ef5918e20817)
#1259 CVE-2026-56409 -- xmlwf: Integer overflow in output path join
#1252 CVE-2026-56410 -- xmlwf: Integer overflow in
`resolveSystemId`
#1263 CVE-2026-56411 -- xmlwf: Integer overflow in notation list
allocation
#1278 CVE-2026-56412 -- Guard XML_TOK_DATA_CHARS handler calls in
`doCdataSection`, plugging a hole in the fix to
CVE-2026-50219
Bug fixes:
#1260 xmlwf: Escape names and base URI in meta output
#1266 xmlwf: Pick a safe quote for notation system and public IDs
Other changes:
#1257 CMake|Autotools: Stop using /dev/urandom by default
#1244 #1254 CMake: Fix guard for Unix sources of entropy
#1183 #1270 CMake|Windows: Add missing export for symbol
`XML_SetHashSalt16Bytes`
#1236 CMake: Mark option EXPAT_OSSFUZZ_BUILD as advanced
#1283 Limit output indentation for EXPAT_ENTITY_DEBUG=1 and
allow unlimited indentation via EXPAT_ENTITY_DEBUG=2
#565 Replace some loops by use of `memcpy`, `strlen`, `wcslen`
#1220 lib: Use a size_t for group sizes
#1221 lib: Fix too-conservative integer overflow check when
appending raw name
#1222 lib: Simplify attribute allocation/management logic
#1224 Update fallthrough annotations to satisfy Clang and GCC
#1226 lib: Remove unnecessary void * casts in random code
#1228 lib: Reduce scope of locals in storeAtts
#1230 lib: Count attributes with size_t variables
#1238 Minor get-buffer improvements
#1239 #1240 lib|tests: Include header expat_config.h first
#1241 lib: Shrink size of XML_GetBuffer
#1242 lib: Remove a legacy comment
#1243 lib: XML_ParserReset: Extract repeated linked-list move logic
#1243 lib: Unify entity free lists
#1247 lib: Fix use of '0' as boolean literal
#1248 lib: Make XML_Index overflow check more intuitive
#1256 lib: Use size_t for counting string/URI lengths
#1258 lib: XML_GetInputContext: Remove use of 0 for NULL
#1261 Comment typo fixes
#1275 Teach Memory Sanitizer semantics of randomization functions
#1276 #1281 Version info bumped from 13:1:12 (libexpat*.so.1.12.1)
to 13:2:12 (libexpat*.so.1.12.2); see https://verbump.de/
for what these numbers do
Infrastructure:
#1231 perl-integration.yml: Bump to XML::Parser 2.59
#1237 emscripten.yml: Bump from Ubuntu 22.04 to 24.04
#1183 #1271 windows-build.yml: Cover completeness of file
libexpat.def.cmake
#1274 linux.yml: Make llvm-symbolizer available in CI
Special thanks to:
Alessandro Gario
Asher Darden
Christoph Reiter
Haris Hussain
Matthew Fernandez
Kartik Kenchi
Nick Begg
Sajin S
Yousef Shanableh
and
Anthropic
Astra Security
Trail of Bits
Release 2.8.1 Sun May 10 2026
Security fixes:
#1216 CVE-2026-45186 -- Fix quadratic runtime from attribute name
collision checks that allowed denial of service attacks
through moderately sized crafted XML input (CWE-407).
Please note that a layer of compression around XML can
significantly reduce the minimum attack payload size.
Upstream CVSS 3.1 vector:
AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H (CVSS score: 7.5)
(Note the "AV:N" for network/remote and the "AC:L"
for low complexity; the NVD entry from Mitre is mistaken.)
Other changes:
#1209 #1213 Drop more casts related to `void *` that C99 does not need
#1213 xmlwf: Streamline use of `mmap`
#1214 #1217 Version info bumped from 13:0:12 (libexpat*.so.1.12.0)
to 13:1:12 (libexpat*.so.1.12.1); see https://verbump.de/
for what these numbers do
Infrastructure:
#1210 CI: Cover compilation with Visual Studio 18 2026 on Windows
#1215 CI: Cover compilation for ARM64 on Windows
#1212 CI: Bump WASI SDK from 32 to 33
Special thanks to:
Berkay Eren Ürün
Matthew Fernandez
Nick Wellnhofer
Tania Somanna
Release 2.8.0 Fri April 24 2026
Security fixes:
#47 #1183 CVE-2026-41080 -- The existing hash flooding protection
(based on SipHash) only used 4 to 8 bytes of entropy for
a salt, when 16 bytes of salt are supported by the
implementation of SipHash used by Expat. Now full 16 bytes
of entropy are used to improve protection against hash
flooding attacks.
Existing API function XML_SetHashSalt is now deprecated
because of its limitations, and its use should be
considered a vulnerability. Please either use the new API
function XML_SetHashSalt16Bytes (with known-high-quality
entropy input only!) instead, or leave the derivation of
a 16-bytes hash salt from high quality entropy to Expat's
internal machinery (by *not* calling either of the two
XML_SetHashSalt* functions).
Bug fixes:
#1188 Avoid propagating /dev/urandom file descriptor to child
processes
#1193 Fix interpretation of `errno` after randomization calls
#1195 Avoid assuming uint8_t is a character type
Other changes:
#1180 #1199 Add support for `getentropy(3)` as a source of entropy;
this helps with protecting against hash flooding attacks,
in particular with WASI SDK (where none of the other
entropy sources supported by libexpat are available).
#1200 Autotools: Add `--without-arc4random` and
`--without-arc4random-buf`
#1200 Autotools: Make `./configure` output report on available
high quality entropy sources
#1173 Autotools|macOS: Sync CMake templates with CMake 4.3.0
#1201 Autotools|CMake: Improve checks for `arc4random` and
`arc4random_buf` e.g. with modern glibc
#1201 CMake: Report on availability of functions `arc4random` and
`arc4random_buf`
#1201 CMake: Mark entropy related build switches as advanced
#1189 ..
#1203 #1204 Extract new files from entropy extraction code
#1194 Stop duplicating C tests 1:1 as C++ ("runtests_cxx")
#1202 Fix a comment typo in expat_external.h
#1187 Fix grammar in compile error message
#1192 examples: Build warning-free with -Wwrite-strings
#1171 tests: Address harmless warning from Coverity
#1170 #1176 Sync file headers
#1190 #1206 Version info bumped from 12:3:11 (libexpat*.so.1.11.3)
to 13:0:12 (libexpat*.so.1.12.0); see https://verbump.de/
for what these numbers do
Infrastructure:
#1166 #1167 ..
#1172 #1175 ..
#1178 #1179 ..
#1185 #1205 CI: Make Perl XML::Parser integration tests run against
both version 2.47 and the latest release 2.58
#1169 CI: Adapt to breaking changes regarding Inno Setup
#1173 CI: Adapt to breaking changes regarding CMake
#1174 CI: Include public corpus of fuzzer `xml_lpm_fuzzer` with
regression testing
#1181 #1182 CI: Bump WASI SDK from 30 to 32
Special thanks to:
Jérôme Duval
Matthew Fernandez
Release 2.7.5 Tue March 17 2026
Security fixes:
#1158 CVE-2026-32776 -- Fix NULL function pointer dereference for
empty external parameter entities; it takes use of both
functions XML_ExternalEntityParserCreate and
XML_SetParamEntityParsing for an application to be
vulnerable.
#1161 #1162 CVE-2026-32777 -- Protect from XML_TOK_INSTANCE_START
infinite loop in function entityValueProcessor; it takes
use of both functions XML_ExternalEntityParserCreate and
XML_SetParamEntityParsing for an application to be
vulnerable.
#1163 CVE-2026-32778 -- Fix NULL dereference in function setContext
on retry after an earlier ouf-of-memory condition; it takes
use of function XML_ParserCreateNS or XML_ParserCreate_MM
for an application to be vulnerable.
#1160 Three more unfixed vulnerabilities left
Other changes:
#1146 #1147 Autotools: Fix condition for symbol versioning check, in
particular when compiling with slibtool (not libtool)
#1156 Address Cppcheck >=2.20.0 warnings
#1153 tests: Make test_buffer_can_grow_to_max work for MinGW on
Ubuntu 24.04
#1157 #1159 Version info bumped from 12:2:11 (libexpat*.so.1.11.2)
to 12:3:11 (libexpat*.so.1.11.3); see https://verbump.de/
for what these numbers do
Infrastructure:
#1148 CI: Fix FreeBSD and Solaris CI
#1149 CI: Bump to WASI SDK 30
#1153 CI: Adapt to breaking changes with Ubuntu 22.04
#1156 CI: Adapt to breaking changes in Cppcheck
Special thanks to:
Berkay Eren Ürün
Christian Ng
Fabio Scaccabarozzi
Francesco Bertolaccini
Mark Brand
Rhodri James
and
AddressSanitizer
Buttercup
OSS-Fuzz / ClusterFuzz
Trail of Bits
Release 2.7.4 Sat January 31 2026
Security fixes:
#1131 CVE-2026-24515 -- Function XML_ExternalEntityParserCreate
failed to copy the encoding handler data passed to
XML_SetUnknownEncodingHandler from the parent to the new
subparser. This can cause a NULL dereference (CWE-476) from
external entities that declare use of an unknown encoding.
The expected impact is denial of service. It takes use of
both functions XML_ExternalEntityParserCreate and
XML_SetUnknownEncodingHandler for an application to be
vulnerable.
#1075 CVE-2026-25210 -- Add missing check for integer overflow
related to buffer size determination in function doContent
Bug fixes:
#1073 lib: Fix missing undoing of group size expansion in doProlog
failure cases
#1107 xmlwf: Fix a memory leak
#1104 WASI: Fix format specifiers for 32bit WASI SDK
Other changes:
#1105 lib: Fix strict aliasing
#1106 lib: Leverage feature "flexible array member" of C99
#1051 lib: Swap (size_t)(-1) for C99 equivalent SIZE_MAX
#1109 lib|xmlwf: Return NULL instead of 0 for pointers
#1068 lib|Windows: Clean up use of macro _MSC_EXTENSIONS with MSVC
#1112 lib: Remove unused import
#1110 xmlwf: Warn about XXE in --help output (and man page)
#1102 #1103 WASI: Stop using getpid
#1113 #1130 Autotools: Drop file expat.m4 that provided obsolete Autoconf
macro AM_WITH_EXPAT
#1123 Autotools: Limit -Wno-pedantic-ms-format to MinGW
#1129 #1134 ..
#1087 Autotools|macOS: Sync CMake templates with CMake 4.0
#1139 #1140 Autotools|CMake: Introduce off-by-default symbol versioning
The related build system flags are:
- For Autotools, configure with --enable-symbol-versioning
- For CMake, configure with -DEXPAT_SYMBOL_VERSIONING=ON
Please double-check for consequences before activating
this inside distro packaging. Bug reports welcome!
#1117 Autotools|CMake: Remove libbsd support
#1105 Autotools|CMake: Stop using -fno-strict-aliasing, and use
-Wstrict-aliasing=3 instead
#1124 Autotools|CMake: Prefer command gsed (GNU sed) over sed
(e.g. for Solaris) inside fix-xmltest-log.sh
#1067 CMake: Detect and warn about unusable check_c_compiler_flag
#1137 CMake: Drop support for CMake <3.17
#1138 CMake|Windows: Fix libexpat.def.cmake version comments
#1086 #1110 docs: Add warning about external reference handlers and XXE
#1066 docs: Be explicit that parent parsers need to outlive
subparsers
#1089 ..
#1090 #1091 ..
#1092 #1093 ..
#1094 #1098 ..
#1115 #1116 docs: Misc non-content improvements to doc/reference.html
#1132 #1133 Version info bumped from 12:1:11 (libexpat*.so.1.11.1)
to 12:2:11 (libexpat*.so.1.11.2); see https://verbump.de/
for what these numbers do
Infrastructure:
#1119 #1121 Document guidelines for contributing to Expat
#1120 Introduce a pull request template
#1074 CI: Stop using about-to-be-removed image "macos-13"
#1083 #1088 CI: Mitigate random Wine crashes
#1104 CI: Cover compilation with WASI SDK
#1116 CI: Enforce clean doc XML formatting
#1124 ..
#1135 #1136 CI: Cover Solaris 11.4
#1125 CI: Extend CI coverage of FreeBSD
#1139 #1140 CI: Cover symbol versioning
#1114 xmlwf: Reformat helpgen code (using Black 25.12.0)
#1071 .gitignore: Add files CPackConfig.cmake and
CPackSourceConfig.cmake
Special thanks to:
Alfonso Gregory
Bénédikt Tran
Gordon Messmer
Hanno Böck
Jakub Kulík
Matthew Fernandez
Neil Pang
Rosen Penev
and
Artiphishell Inc.
Release 2.7.3 Wed September 24 2025
Security fixes:
#1046 #1048 Fix alignment of internal allocations for some non-amd64
architectures (e.g. sparc32); fixes up on the fix to
CVE-2025-59375 from #1034 (of Expat 2.7.2 and related
backports)
#1059 Fix a class of false positives where input should have been
rejected with error XML_ERROR_ASYNC_ENTITY; regression from
CVE-2024-8176 fix pull request #973 (of Expat 2.7.0 and
related backports). Please check the added unit tests for
example documents.
Other changes:
#1043 Prove and regression-proof absence of integer overflow
from function expat_realloc
#1062 Remove "harmless" cast that truncated a size_t to unsigned
#1049 Autotools: Remove "ln -s" discovery
#1054 docs: Be consistent with use of floating point around
XML_SetAllocTrackerMaximumAmplification
#1056 docs: Make it explicit that XML_GetCurrentColumnNumber
starts at 0
#1057 docs: Better integrate the effect of the activation
thresholds
#1058 docs: Fix an in-comment typo in expat.h
#1045 docs: Fix a typo in README.md
#1041 docs: Improve change log of release 2.7.2
#1053 xmlwf: Resolve use of functions XML_GetErrorLineNumber
and XML_GetErrorColumnNumber
#1032 Windows: Normalize .bat files to CRLF line endings
#1060 #1061 Version info bumped from 12:0:11 (libexpat*.so.1.11.0)
to 12:1:11 (libexpat*.so.1.11.1); see https://verbump.de/
for what these numbers do
Infrastructure:
#1047 #1050 CI: Cleanup UndefinedBehaviorSanitizer fatality
#1044 CI|Linux: Stop aborting at first job failure
#1052 CI|FreeBSD: Upgrade to FreeBSD 15.0
#1039 CI|FreeBSD: Do not install CMake meta-package
Special thanks to:
Bénédikt Tran
Berkay Eren Ürün
Daniel Engberg
Hanno Böck
Matthew Fernandez
Rolf Eike Beer
Sam James
Tim Bray
and
Clang/GCC UndefinedBehaviorSanitizer
OSS-Fuzz / ClusterFuzz
Z3 Theorem Prover
Release 2.7.2 Tue September 16 2025
Security fixes:
#1018 #1034 CVE-2025-59375 -- Disallow use of disproportional amounts of
dynamic memory from within an Expat parser (e.g. previously
a ~250 KiB sized document was able to cause allocation of
~800 MiB from the heap, i.e. an "amplification" of factor
~3,300); once a threshold (that defaults to 64 MiB) is
reached, a maximum amplification factor (that defaults to
100.0) is enforced, and violating documents are rejected
with an out-of-memory error.
There are two new API functions to fine-tune this new
behavior:
- XML_SetAllocTrackerActivationThreshold
- XML_SetAllocTrackerMaximumAmplification .
If you ever need to increase these defaults for non-attack
XML payload, please file a bug report with libexpat.
There is also a new environment variable
EXPAT_MALLOC_DEBUG=(0|1|2) to control the verbosity
of allocations debugging at runtime, disabled by default.
Known impact is (reliable and easy) denial of service:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:H/RL:O/RC:C
(Base Score: 7.5, Temporal Score: 7.2)
Please note that a layer of compression around XML can
significantly reduce the minimum attack payload size.
Distributors intending to backport (or cherry-pick) the
fix need to copy 99% of the related pull request, not just
the "lib: Implement tracking of dynamic memory allocations"
commit, to not end up with a state that literally does both
too much and too little at the same time. Appending ".diff"
to the pull request URL could be of help.
Other changes:
#1008 #1017 Autotools|macOS: Sync CMake templates with CMake 3.31
#1007 CMake: Drop support for CMake <3.15
#1004 CMake: Fix off_t detection for -Werror
#1007 CMake|Windows: Fix -DEXPAT_MSVC_STATIC_CRT=ON
#1013 Windows: Drop support for Visual Studio <=16.0/2019
#1026 xmlwf: Mention supported environment variables in
--help output
#1024 xmlwf: Fix (internal) help generator
#1034 docs: Promote the contract to call function
XML_FreeContentModel when registering a custom
element declaration handler (via a call to function
XML_SetElementDeclHandler)
#1027 docs: Add missing <p>..</p> wrap
#994 docs: Drop AppVeyor badge
#1000 tests: Fix portable_strndup
#1036 Drop casts around malloc/free/realloc that C99 does not need
#1010 Replace empty for loops with while loops
#1011 Add const with internal XmlInitUnknownEncodingNS
#14 #1037 Drop an OpenVMS support leftover
#999 #1001 Address more clang-tidy warnings
#1030 #1038 Version info bumped from 11:2:10 (libexpat*.so.1.10.2)
to 12:0:11 (libexpat*.so.1.11.0); see https://verbump.de/
for what these numbers do
Infrastructure:
#1003 CI: Cover compilation on FreeBSD
#1009 #1035 CI: Upgrade Clang from 19 to 21
#1031 CI: Make calling Cppcheck without --suppress=objectIndex
and --suppress=unknownMacro possible
#1013 CI|Windows: Get off of deprecated image "windows-2019"
#1008 #1017 ..
#1023 #1025 CI: Adapt to breaking changes in GitHub Actions
Special thanks to:
Alexander Bluhm
Neil Pang
Theo Buehler
and
GNU Time
OSS-Fuzz / ClusterFuzz
Perl XML::Parser
Release 2.7.1 Thu March 27 2025
Bug fixes:
#980 #989 Restore event pointer behavior from Expat 2.6.4
(that the fix to CVE-2024-8176 changed in 2.7.0);
affected API functions are:
- XML_GetCurrentByteCount
- XML_GetCurrentByteIndex
- XML_GetCurrentColumnNumber
- XML_GetCurrentLineNumber
- XML_GetInputContext
Other changes:
#976 #977 Autotools: Integrate files "fuzz/xml_lpm_fuzzer.{cpp,proto}"
with Automake that were missing from 2.7.0 release tarballs
#983 #984 Fix printf format specifiers for 32bit Emscripten
#992 docs: Promote OpenSSF Best Practices self-certification
#978 tests/benchmark: Resolve mistaken double close
#986 Address Frama-C warnings
#990 #993 Version info bumped from 11:1:10 (libexpat*.so.1.10.1)
to 11:2:10 (libexpat*.so.1.10.2); see https://verbump.de/
for what these numbers do
Infrastructure:
#982 CI: Start running Perl XML::Parser integration tests
#987 CI: Enforce Clang Static Analyzer clean code
#991 CI: Re-enable warning clang-analyzer-valist.Uninitialized
for clang-tidy
#981 CI: Cover compilation with musl
#983 #984 CI: Cover compilation with 32bit Emscripten
#976 #977 CI: Protect against fuzzer files missing from future
release archives
Special thanks to:
Berkay Eren Ürün
Matthew Fernandez
and
Perl XML::Parser
Release 2.7.0 Thu March 13 2025
Security fixes:
#893 #973 CVE-2024-8176 -- Fix crash from chaining a large number
of entities caused by stack overflow by resolving use of
recursion, for all three uses of entities:
- general entities in character data ("<e>&g1;</e>")
- general entities in attribute values ("<e k1='&g1;'/>")
- parameter entities ("%p1;")
Known impact is (reliable and easy) denial of service:
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:H/RL:O/RC:C
(Base Score: 7.5, Temporal Score: 7.2)
Please note that a layer of compression around XML can
significantly reduce the minimum attack payload size.
Other changes:
#935 #937 Autotools: Make generated CMake files look for
libexpat.@SO_MAJOR@.dylib on macOS
#925 Autotools: Sync CMake templates with CMake 3.29
#945 #962 #966 CMake: Drop support for CMake <3.13
#942 CMake: Small fuzzing related improvements
#921 docs: Add missing documentation of error code
XML_ERROR_NOT_STARTED that was introduced with 2.6.4
#941 docs: Document need for C++11 compiler for use from C++
#959 tests/benchmark: Fix a (harmless) TOCTTOU
#944 Windows: Fix installer target location of file xmlwf.xml
for CMake
#953 Windows: Address warning -Wunknown-warning-option
about -Wno-pedantic-ms-format from LLVM MinGW
#971 Address Cppcheck warnings
#969 #970 Mass-migrate links from http:// to https://
#947 #958 ..
#974 #975 Document changes since the previous release
#974 #975 Version info bumped from 11:0:10 (libexpat*.so.1.10.0)
to 11:1:10 (libexpat*.so.1.10.1); see https://verbump.de/
for what these numbers do
Infrastructure:
#926 tests: Increase robustness
#927 #932 ..
#930 #933 tests: Increase test coverage
#617 #950 ..
#951 #952 ..
#954 #955 .. Fuzzing: Add new fuzzer "xml_lpm_fuzzer" based on
#961 Google's libprotobuf-mutator ("LPM")
#957 Fuzzing|CI: Start producing fuzzing code coverage reports
#936 CI: Pass -q -q for LCOV >=2.1 in coverage.sh
#942 CI: Small fuzzing related improvements
#139 #203 ..
#791 #946 CI: Make GitHub Actions build using MSVC on Windows and
produce 32bit and 64bit Windows binaries
#956 CI: Get off of about-to-be-removed Ubuntu 20.04
#960 #964 CI: Start uploading to Coverity Scan for static analysis
#972 CI: Stop loading DTD from the internet to address flaky CI
#971 CI: Adapt to breaking changes in Cppcheck
Special thanks to:
Alexander Gieringer
Berkay Eren Ürün
Hanno Böck
Jann Horn
Mark Brand
Sebastian Andrzej Siewior
Snild Dolkow
Thomas Pröll
Tomas Korbar
valord577
and
Google Project Zero
Linutronix
Red Hat
Siemens
Release 2.6.4 Wed November 6 2024
Security fixes:
#915 CVE-2024-50602 -- Fix crash within function XML_ResumeParser
from a NULL pointer dereference by disallowing function
XML_StopParser to (stop or) suspend an unstarted parser.
A new error code XML_ERROR_NOT_STARTED was introduced to
properly communicate this situation. // CWE-476 CWE-754
Other changes:
#903 CMake: Add alias target "expat::expat"
#905 docs: Document use via CMake >=3.18 with FetchContent
and SOURCE_SUBDIR and its consequences
#902 tests: Reduce use of global parser instance
#904 tests: Resolve duplicate handler
#317 #918 tests: Improve tests on doctype closing (ex CVE-2019-15903)
#914 Fix signedness of format strings
#915 For use from C++, expat.h started requiring C++11 due to
use of C99 features
#919 #920 Version info bumped from 10:3:9 (libexpat*.so.1.9.3)
to 11:0:10 (libexpat*.so.1.10.0); see https://verbump.de/
for what these numbers do
Infrastructure:
#907 CI: Upgrade Clang from 18 to 19
#913 CI: Drop macos-12 and add macos-15
#910 CI: Adapt to breaking changes in GitHub Actions
#898 Add missing entries to .gitignore
Special thanks to:
Hanno Böck
José Eduardo Gutiérrez Conejo
José Ricardo Cardona Quesada
Release 2.6.3 Wed September 4 2024
Security fixes:
#887 #890 CVE-2024-45490 -- Calling function XML_ParseBuffer with
len < 0 without noticing and then calling XML_GetBuffer
will have XML_ParseBuffer fail to recognize the problem
and XML_GetBuffer corrupt memory.
With the fix, XML_ParseBuffer now complains with error
XML_ERROR_INVALID_ARGUMENT just like sibling XML_Parse
has been doing since Expat 2.2.1, and now documented.
Impact is denial of service to potentially artitrary code
execution.
#888 #891 CVE-2024-45491 -- Internal function dtdCopy can have an
integer overflow for nDefaultAtts on 32-bit platforms
(where UINT_MAX equals SIZE_MAX).
Impact is denial of service to potentially artitrary code
execution.
#889 #892 CVE-2024-45492 -- Internal function nextScaffoldPart can
have an integer overflow for m_groupSize on 32-bit
platforms (where UINT_MAX equals SIZE_MAX).
Impact is denial of service to potentially artitrary code
execution.
Other changes:
#851 #879 Autotools: Sync CMake templates with CMake 3.28
#853 Autotools: Always provide path to find(1) for portability
#861 Autotools: Ensure that the m4 directory always exists.
#870 Autotools: Simplify handling of SIZEOF_VOID_P
#869 Autotools: Support non-GNU sed
#856 Autotools|CMake: Fix main() to main(void)
#865 Autotools|CMake: Fix compile tests for HAVE_SYSCALL_GETRANDOM
#863 Autotools|CMake: Stop requiring dos2unix
#854 #855 CMake: Fix check for symbols size_t and off_t
#864 docs|tests: Convert README to Markdown and update
#741 Windows: Drop support for Visual Studio <=15.0/2017
#886 Drop needless XML_DTD guards around is_param access
#885 Fix typo in a code comment
#894 #896 Version info bumped from 10:2:9 (libexpat*.so.1.9.2)
to 10:3:9 (libexpat*.so.1.9.3); see https://verbump.de/
for what these numbers do
Infrastructure:
#880 Readme: Promote the call for help
#868 CI: Fix various issues
#849 CI: Allow triggering GitHub Actions workflows manually
#851 #872 ..
#873 #879 CI: Adapt to breaking changes in GitHub Actions
Special thanks to:
Alexander Bluhm
Berkay Eren Ürün
Dag-Erling Smørgrav
Ferenc Géczi
TaiYou
Release 2.6.2 Wed March 13 2024
Security fixes:
#839 #842 CVE-2024-28757 -- Prevent billion laughs attacks with
isolated use of external parsers. Please see the commit
message of commit 1d50b80cf31de87750103656f6eb693746854aa8
for details.
Bug fixes:
#839 #841 Reject direct parameter entity recursion
and avoid the related undefined behavior
Other changes:
#847 Autotools: Fix build for DOCBOOK_TO_MAN containing spaces
#837 Add missing #821 and #824 to 2.6.1 change log
#838 #843 Version info bumped from 10:1:9 (libexpat*.so.1.9.1)
to 10:2:9 (libexpat*.so.1.9.2); see https://verbump.de/
for what these numbers do
Special thanks to:
Philippe Antoine
Tomas Korbar
and
Clang UndefinedBehaviorSanitizer
OSS-Fuzz / ClusterFuzz
Release 2.6.1 Thu February 29 2024
Bug fixes:
#817 Make tests independent of CPU speed, and thus more robust
#828 #836 Expose billion laughs API with XML_DTD defined and
XML_GE undefined, regression from 2.6.0
Other changes:
#829 Hide test-only code behind new internal macro
#833 Autotools: Reject expat_config.h.in defining SIZEOF_VOID_P
#821 #824 Autotools: Fix "make clean" for case:
./configure --without-docbook && make clean all
#819 Address compiler warnings
#832 #834 Version info bumped from 10:0:9 (libexpat*.so.1.9.0)
to 10:1:9 (libexpat*.so.1.9.1); see https://verbump.de/
for what these numbers do
Infrastructure:
#818 CI: Adapt to breaking changes in clang-format
Special thanks to:
David Hall
Snild Dolkow
Release 2.6.0 Tue February 6 2024
Security fixes:
#789 #814 CVE-2023-52425 -- Fix quadratic runtime issues with big tokens
that can cause denial of service, in partial where
dealing with compressed XML input. Applications
that parsed a document in one go -- a single call to
functions XML_Parse or XML_ParseBuffer -- were not affected.
The smaller the chunks/buffers you use for parsing
previously, the bigger the problem prior to the fix.
Backporters should be careful to no omit parts of
pull request #789 and to include earlier pull request #771,
in order to not break the fix.
#777 CVE-2023-52426 -- Fix billion laughs attacks for users
compiling *without* XML_DTD defined (which is not common).
Users with XML_DTD defined have been protected since
Expat >=2.4.0 (and that was CVE-2013-0340 back then).
Bug fixes:
#753 Fix parse-size-dependent "invalid token" error for
external entities that start with a byte order mark
#780 Fix NULL pointer dereference in setContext via
XML_ExternalEntityParserCreate for compilation with
XML_DTD undefined
#812 #813 Protect against closing entities out of order
Other changes:
#723 Improve support for arc4random/arc4random_buf
#771 #788 Improve buffer growth in XML_GetBuffer and XML_Parse
#761 #770 xmlwf: Support --help and --version
#759 #770 xmlwf: Support custom buffer size for XML_GetBuffer and read
#744 xmlwf: Improve language and URL clickability in help output
#673 examples: Add new example "element_declarations.c"
#764 Be stricter about macro XML_CONTEXT_BYTES at build time
#765 Make inclusion to expat_config.h consistent
#726 #727 Autotools: configure.ac: Support --disable-maintainer-mode
#678 #705 ..
#706 #733 #792 Autotools: Sync CMake templates with CMake 3.26
#795 Autotools: Make installation of shipped man page doc/xmlwf.1
independent of docbook2man availability
#815 Autotools|CMake: Add missing -DXML_STATIC to pkg-config file
section "Cflags.private" in order to fix compilation
against static libexpat using pkg-config on Windows
#724 #751 Autotools|CMake: Require a C99 compiler
(a de-facto requirement already since Expat 2.2.2 of 2017)
#793 Autotools|CMake: Fix PACKAGE_BUGREPORT variable
#750 #786 Autotools|CMake: Make test suite require a C++11 compiler
#749 CMake: Require CMake >=3.5.0
#672 CMake: Lowercase off_t and size_t to help a bug in Meson
#746 CMake: Sort xmlwf sources alphabetically
#785 CMake|Windows: Fix generation of DLL file version info
#790 CMake: Build tests/benchmark/benchmark.c as well for
a build with -DEXPAT_BUILD_TESTS=ON
#745 #757 docs: Document the importance of isFinal + adjust tests
accordingly
#736 docs: Improve use of "NULL" and "null"
#713 docs: Be specific about version of XML (XML 1.0r4)
and version of C (C99); (XML 1.0r5 will need a sponsor.)
#762 docs: reference.html: Promote function XML_ParseBuffer more
#779 docs: reference.html: Add HTML anchors to XML_* macros
#760 docs: reference.html: Upgrade to OK.css 1.2.0
#763 #739 docs: Fix typos
#696 docs|CI: Use HTTPS URLs instead of HTTP at various places
#669 #670 ..
#692 #703 ..
#733 #772 Address compiler warnings
#798 #800 Address clang-tidy warnings
#775 #776 Version info bumped from 9:10:8 (libexpat*.so.1.8.10)
to 10:0:9 (libexpat*.so.1.9.0); see https://verbump.de/
for what these numbers do
Infrastructure:
#700 #701 docs: Document security policy in file SECURITY.md
#766 docs: Improve parse buffer variables in-code documentation
#674 #738 ..
#740 #747 ..