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Responses with QDCOUNT=0 bypass check for matching question section

Low
divergentdave published GHSA-3w89-7rx5-hpwx Sep 3, 2026

Package

cargo hickory-net (Rust)

Affected versions

0.26.0 .. 0.26.1

Patched versions

0.26.2
cargo hickory-proto (Rust)
0.25.0 .. 0.25.2
None

Description

If a UDP client connection receives a response with an empty question section, the intended check for matching question sections in queries and responses is skipped. If case_randomization is enabled, the check for matching capitalization of query names is skipped as well. This removes one layer of defense in depth against spoofing attacks.

Severity

Low

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
High
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:N

CVE ID

No known CVE

Weaknesses

Authentication Bypass by Spoofing

This attack-focused weakness is caused by incorrectly implemented authentication schemes that are subject to spoofing attacks. Learn more on MITRE.

Incorrect Comparison

The product compares two entities in a security-relevant context, but the comparison is incorrect, which may lead to resultant weaknesses. Learn more on MITRE.

Credits