Executive brief
A race condition flaw in the Linux Kernel is being actively exploited by attackers to compromise systems. This vulnerability allows attackers to gain complete control of affected systems, making it a critical target for organizations to patch immediately. Federal agencies are required to prioritize fixing this issue on any externally facing infrastructure under Binding Operational Directive 26-04.
Technical details
CVE-2025-39964 is a race condition vulnerability in the Linux Kernel that has been confirmed as actively exploited in the wild and added to CISA's Known Exploited Vulnerabilities Catalog. Race condition vulnerabilities typically arise from improper synchronization of concurrent operations, allowing attackers to exploit timing windows to corrupt kernel state or bypass security controls. The vulnerability is reachable over the network or through local access depending on the specific kernel subsystem affected. Successful exploitation grants total control of the affected system, enabling arbitrary code execution at kernel privilege level. Organizations should apply vendor-supplied kernel patches immediately, particularly on publicly exposed systems. CISA provides detailed mitigation guidance and monitoring recommendations for this vulnerability.
Affected products
- Linux Kernel <UNKNOWN>
Timeline
- 2026-09-18: disclosed
- 2026-09-18: kev added