Linux Kernel Race Condition Vulnerability
This vulnerability is in the CISA Known Exploited Vulnerabilities catalog: attackers are using it. If you run Linux, fix it now.
CISA required action: Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.
US federal civilian agencies must remediate by Sep 21, 2026.
Official fix available since
Apply the vendor's update to every affected system. Check the fixed-in versions below where known.
Basis: NVD patch reference
In the Linux kernel, the following vulnerability has been resolved: crypto: af_alg - Disallow concurrent writes in af_alg_sendmsg Issuing two writes to the same af_alg socket is bogus as the data will be interleaved in an unpredictable fashion. Furthermore, concurrent writes may create inconsistencies in the internal socket state. Disallow this by adding a new ctx->write field that indiciates exclusive ownership for writing.
Source: NIST National Vulnerability Database. Official vulnerability data, reproduced as published.
| Product | Vendor | Affected versions | Fixed in | Source |
|---|---|---|---|---|
| Linux | Linux | >= 2.6.38, < 5.10.245; >= 5.11, < 5.15.194; >= 5.16, < 6.1.154; >= 6.2, < 6.6.108; >= 6.7, < 6.12.49; >= 6.13, < 6.16.9 | 5.10.245; 5.15.194; 6.1.154; 6.6.108; 6.12.49; 6.16.9 | KEV |
Sources: KEV = CISA Known Exploited Vulnerabilities catalog.
Developments from the last 30 days, newest first.
CVE-2025-39964 scored CVSS 5.5: Linux Kernel, Linux Kernel Race Condition Vulnerability
CISA lists this as exploited in the wild. Unpatched Kernel systems are exposed to active attacks now.
Basis: NIST National Vulnerability Database
Patch released for CVE-2025-39964: Linux Kernel, Linux Kernel Race Condition Vulnerability
An official fix is now available for Linux Kernel. This vulnerability is being exploited, so apply it promptly.
Basis: NVD patch reference
CVE-2025-39964 added to CISA KEV: Linux Kernel, Linux Kernel Race Condition Vulnerability
CISA lists this as exploited in the wild. Unpatched Kernel systems are exposed to active attacks now.
Basis: CISA Known Exploited Vulnerabilities catalog
CISA lists this as exploited in the wild. Unpatched Linux systems are exposed to active attacks now.
Apply the vendor's security update for Linux.
