CVE-2025-39964 Linux CVE debrief

Who should care

System administrators and security teams responsible for Linux Kernel deployments should assess exposure and apply mitigations in accordance with vendor instructions. The vulnerability requires immediate attention from system administrators and security teams. The vulnerability affects the Linux Kernel and is known to be exploited in the wild. System administrators and security teams should review compensating

Why it matters

The Linux Kernel race condition vulnerability requires immediate attention from system administrators and security teams. The vulnerability is known to be exploited in the wild, and applying mitigations in accordance with vendor instructions is crucial to prevent potential exploitation.

• Verify and apply vendor-provided patches or mitigations
• Ensure compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk guidance
• Follow CISA’s Forensics Triage Requirements

Technical summary

The Linux Kernel is vulnerable to a race condition, which could allow an attacker to potentially exploit the vulnerability. The vulnerability affects the Linux Kernel and is known to be exploited in the wild. There is limited information available about the vulnerability, and defenders should verify the affected scope and apply mitigations in accordance with vendor instructions. The CVE record was published on 2026-09-18T00:00:00.000Z and has not been modified since then.

Defensive priority

Apply mitigations in accordance with vendor instructions

Recommended defensive actions

• Apply mitigations in accordance with vendor instructions
• Ensure compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk guidance
• Follow CISA’s Forensics Triage Requirements

Evidence notes

The vulnerability affects the Linux Kernel and is known to be exploited in the wild. There is limited information available about the vulnerability, and defenders should verify the affected scope and apply mitigations in accordance with vendor instructions. The CVE record was published on 2026-09-18T00:00:00.000Z and has not been modified since then. The NVD entry is currently being reviewed. System administrators and security teams should assess exposure and apply mitigations. The

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.