Actively exploited
Listed in CISA’s Known Exploited Vulnerabilities catalog since September 18, 2026.
CVE-2025-39964
Linux Kernel Race Condition Vulnerability
Added to KEV September 18, 2026
Alert details
- Source feed
- CISA KEV
- CVE ID
- CVE-2025-39964
- CWE
- CWE-362
- Affected products
- Kernel · Linux Kernel · Linux
What happened
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.
What it means for your business
Linux Kernel is listed in CISA's Known Exploited Vulnerabilities catalog (CVE-2025-39964). 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. CISA remediation due date: 2026-09-21. If you need help checking exposure, call (864) 335-9223.
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.
CISA due date: September 21, 2026
Sources
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