In the Linux kernel, the following vulnerability has been resolved: sctp: Fix MAC comparison to be constant-time To prevent timing attacks, MACs… (CVE-2025-40204)
A vulnerability in the Linux kernel SCTP implementation involved a non-constant-time comparison of MACs, which could allow timing attacks. The issue has been resolved by updating the MAC comparison to use a constant-time helper function to prevent such attacks.
AI Analysis
Technical Summary
The Linux kernel SCTP subsystem had a vulnerability (CVE-2025-40204) where Message Authentication Codes (MACs) were compared in a way that was not constant-time, potentially enabling timing attacks. This flaw was addressed by modifying the code to use an appropriate constant-time comparison helper function, mitigating the timing attack vector.
Potential Impact
Successful exploitation could allow an attacker to infer MAC values through timing analysis, potentially compromising message integrity and authentication. The CVSS vector indicates network attack complexity is high, no privileges or user interaction required, and the impact on confidentiality, integrity, and availability is high.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to address this vulnerability by using constant-time MAC comparison. Users should apply the official kernel updates that include this fix. Since this is a kernel-level issue, updating to the patched kernel version is the recommended remediation.
In the Linux kernel, the following vulnerability has been resolved: sctp: Fix MAC comparison to be constant-time To prevent timing attacks, MACs… (CVE-2025-40204)
Description
A vulnerability in the Linux kernel SCTP implementation involved a non-constant-time comparison of MACs, which could allow timing attacks. The issue has been resolved by updating the MAC comparison to use a constant-time helper function to prevent such attacks.
CVSS v3.1
Score 8.1high
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The Linux kernel SCTP subsystem had a vulnerability (CVE-2025-40204) where Message Authentication Codes (MACs) were compared in a way that was not constant-time, potentially enabling timing attacks. This flaw was addressed by modifying the code to use an appropriate constant-time comparison helper function, mitigating the timing attack vector.
Potential Impact
Successful exploitation could allow an attacker to infer MAC values through timing analysis, potentially compromising message integrity and authentication. The CVSS vector indicates network attack complexity is high, no privileges or user interaction required, and the impact on confidentiality, integrity, and availability is high.
Mitigation Recommendations
A fix has been implemented in the Linux kernel to address this vulnerability by using constant-time MAC comparison. Users should apply the official kernel updates that include this fix. Since this is a kernel-level issue, updating to the patched kernel version is the recommended remediation.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-4xv3-7wp7-qjp7
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2025-40204"]
- Database Specific Severity
- HIGH
- Cvss Version
- 3.1
Threat ID: 6a6b72d69c2644c7f847a592
Added to database: 07/30/2026, 15:50:46 UTC
Last enriched: 07/30/2026, 16:53:45 UTC
Last updated: 09/10/2026, 19:38:44 UTC
Views: 11
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