Exploited vulnerability CISA KEV
CVE-2025-39964: Linux Kernel Race Condition Vulnerability
CVE-2025-39964 is a vulnerability in Linux Kernel that CISA added to its Known Exploited Vulnerabilities catalog on September 18, 2026, meaning there is evidence it is being exploited. US federal civilian agencies must complete the required action by September 21, 2026.
CVE-2025-39964 is a vulnerability in Linux Kernel that CISA added to its Known Exploited Vulnerabilities catalog on September 18, 2026, meaning there is evidence it is being exploited. US federal civilian agencies must complete the required action by September 21, 2026.
- CVE ID
- CVE-2025-39964
- Vendor / project
- Linux
- Product
- Kernel
- Added to KEV
- Due date
- Days to remediate
- 3
- Known ransomware use
- Unknown
- Weakness
- CWE-362
CISA description #
Linux Kernel contains a race condition vulnerability which allows concurrent writes to the same AF_ALG socket causing data to be unpredictably interleaved and creating inconsistencies in the socket's internal state.
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.
Notes and references #
This vulnerability affects an open-source component, third-party library, protocol, or proprietary implementation that could be used by different products. For more information, please see: ; https://git.kernel.org/stable/c/0f28c4adbc4a97437874c9b669fd7958a8c6d6ce; https://git.kernel.org/stable/c/e4c1ec11132ec466f7362a95f36a506ce4dc08c9; https://git.kernel.org/stable/c/1f323a48e9b5ebfe6dc7d130fdf5c3c0e92a07c8; https://git.kernel.org/stable/c/7c4491b5644e3a3708f3dbd7591be0a570135b84; https://git.kernel.org/stable/c/9aee87da5572b3a14075f501752e209801160d3d; https://git.kernel.org/stable/c/45bcf60fe49b37daab1acee57b27211ad1574042; https://git.kernel.org/stable/c/1b34cbbf4f011a121ef7b2d7d6e6920a036d5285 ; BOD 26-04: https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk ; Forensics Triage Requirements: https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk ; https://nvd.nist.gov/vuln/detail/CVE-2025-39964
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