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Exploited. On CISA's list since 2026-08-26.
CVE-2015-3246 · Red Hat Libuser · Published 2015-08-11
7.4 out of 10
CVSS rates it high.
8.5%
Estimated chance of exploitation in the next 30 days, higher than 95% of all scored flaws (EPSS, 2026-10-29).
Yes
CISA has seen it exploited in real attacks. For US government agencies the fix is deadline passed 51 days ago (2026-09-09).
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.
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.
libuser before 0.56.13-8 and 0.60 before 0.60-7, as used in the userhelper program in the usermode package, directly modifies /etc/passwd, which allows local users to cause a denial of service (inconsistent file state) by causing an error during the modification. NOTE: this issue can be combined with CVE-2015-3245 to gain privileges.
From the NVD.
Explore this week’s weaknesses and all learning topics
Understand the kind of weakness behind this flaw. These resources teach the weakness, rather than reproduce this specific CVE. Follow the vendor's advice above to fix the affected product.
Another operation changes shared state between a check and the action that relies on it.
CWE-367 · NVD record: 134c704f-9b21-4f2e-91b3-4a467353bcc0
Video course · Free course. C programming and memory concepts are useful; covers several weakness types.
CWE-264 · NVD record: nvd@nist.gov. We have not selected a close learning match for this label.
CWE is a catalogue of weakness types. Labels come from the sources shown and can differ or change. Resource matches reviewed 16 October 2026.
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Exploited flaws from CISA's KEV catalogue. Chance of exploitation from EPSS by FIRST. Descriptions and scores from the NVD. This product uses the NVD API but is not endorsed or certified by the NVD.