Red Hat Libuser Race Condition Vulnerability
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…
Severity = CVSS. Probability = EPSS (FIRST). Exploitation = public signals: KEV, EUVD, ransomware, EPSS above 10 %, no account required.
Exploitation probability EPSS · FIRST
Exploitation signals 2 / 5
- KEV catalog (CISA)26 Aug 2026
- Exploited in EUVD (ENISA)26 Aug 2026
- Used by ransomwareno
- EPSS above 10 %8.5%
- No account, over the networkno
What to do
Fix
Apply the vendor’s fix as soon as it is available.
CISA guidance: 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.
Meanwhile
Take the service off the internet or restrict access to it, watch the logs and look for signs of compromise.
Manufacturers (CRA)
Exploited vulnerability in your product: early warning to ENISA within 24 h, then notification within 72 h (Article 14 of the Cyber Resilience Act). The CRA explained
Description ENISA EUVD
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.
Affected products
Open source packages OSV
Affected libraries according to OSV, with fixed versions.
Timeline
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Published
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Exploitation reported (ENISA)
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Added to the KEV catalog
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CISA remediation due date
References
Other exploited vulnerabilities from the same vendor
- CVE-2015-5287Red Hat Automatic Bug Reporting Tool Privilege Escalation Vulnerability4.5 · Actively exploited
- CVE-2018-14667Red Hat JBoss RichFaces Framework Expression Language Injection Vulnerability8.5 · Background exploitation
- CVE-2021-3560Red Hat Polkit Incorrect Authorization Vulnerability5.6 · Background exploitation
- CVE-2021-4034Red Hat Polkit Out-of-Bounds Read and Write Vulnerability8.4 · Background exploitation
- CVE-2010-1428Red Hat JBoss Information Disclosure Vulnerability6.9 · Background exploitation
- CVE-2010-0738Red Hat JBoss Authentication Bypass Vulnerability6.7 · Background exploitation