← gociux.comall exploited CVEs

Exploited vulnerability · CISA KEV

Is CVE-2025-39964 exploited? Yes: in CISA KEV since 18 Sep 2026

Gociux · Linux Kernel · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2025-39964, Linux Kernel Race Condition Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 18 Sep 2026, 340 days after it was published. It affects Linux Kernel. If you run it, CISA's required action is: 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.

exploitedYesCISA KEV · 18 Sep 2026
ransomwareNot knownno confirmed use
EPSSbelow top 10%lower predicted activity right now (it is still confirmed exploited)
severity7.8CVSS 3.1 · high
US federal due21 Sep 2026BOD 22-01 deadline

What it is

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.

VendorLinux (32 exploited CVEs in KEV)
ProductKernel
VulnerabilityLinux Kernel Race Condition Vulnerability
WeaknessCWE-362
Published13 Oct 2025
Added to KEV18 Sep 2026
Reported by (CNA)Linux

What to do

  1. Check whether you run it. Look for Kernel in your asset inventory, including appliances and cloud images. Stack check lists every exploited Linux CVE at once.
  2. Apply the fix. 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.
  3. If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 13 Oct 2025.
  4. Get told next time. Email alerts when CISA adds a CVE for Linux.

Other exploited CVEs in Kernel

References

Questions

Is CVE-2025-39964 being exploited?

Yes. CISA added CVE-2025-39964 to the Known Exploited Vulnerabilities catalog on 18 Sep 2026, which means there is reliable evidence of exploitation in the wild.

Is CVE-2025-39964 used in ransomware attacks?

CISA does not list known ransomware use for it. That can change, and exploitation alone is reason to fix it first.

How do I fix CVE-2025-39964?

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. Check Linux's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected Kernel and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in September 2026 · Linux scorecard · act-now radar.

Running Linux in a regulated environment?

We check exposure across your estate, patch or mitigate with your team, and set up detection for what attackers do after exploiting it.

Get in touch →