Exploited vulnerability · CISA KEV

Is CVE-2015-3246 exploited? Yes: in CISA KEV since 26 Aug 2026

Gociux · Red Hat Libuser · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2015-3246, Red Hat Libuser Race Condition Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 26 Aug 2026, 4033 days after it was published. It affects Red Hat Libuser. 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.

What it is

Red Hat libuser contains a race condition vulnerability that allows authenticated local users to corrupt the /etc/passwd file to cause a denial of service or privilege escalation.

What to do

1. Check whether you run it. Look for Libuser in your asset inventory, including appliances and cloud images. Stack check lists every exploited Red Hat 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 11 Aug 2015.
4. Get told next time. Email alerts when CISA adds a CVE for Red Hat.

References

• nvd.nist.gov/vuln/detail/CVE-2015-3246

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 August 2026 · Red Hat scorecard · act-now radar.