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Infinite Loop in GIF Decoder When Skipping Malformed Comment Extension Blocks

Moderate
JimBobSquarePants published GHSA-rxmq-m78w-7wmc Jul 30, 2025

Package

nuget SixLabors.ImageSharp (NuGet)

Affected versions

< 2.1.11
< 3.1.11

Patched versions

2.1.11
3.1.11

Description

Impact

A specially crafted GIF file containing a malformed comment extension block (with a missing block terminator) can cause the ImageSharp GIF decoder to enter an infinite loop while attempting to skip the block. This leads to a denial of service. Applications processing untrusted GIF input should upgrade to a patched version.

Patches

The problem has been patched. All users are advised to upgrade to v3.1.11 or v2.1.11.

Workarounds

None.

References

#2953

Severity

Moderate

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
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVE ID

CVE-2025-54575

Weaknesses

No CWEs

Credits