---
title: "CVE-2015-3246: Red Hat Libuser Race Condition Vulnerability"
url: https://erroneo.us/security/cve/CVE-2015-3246/
description: "CVE-2015-3246 (Red Hat Libuser): Exploited in the wild (CISA KEV). libuser before 0.56.13-8 and 0.60 before 0.60-7, as used in the userhelper program in the…"
type: vulnerability-record
section: "Security Digest"
date_published: 2015-08-11
date_modified: 2026-10-01
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2015-3246"
kev: true
cvss: 7.4
epss: 0.08503
license: All rights reserved. Quote with attribution and a link.
---

# CVE-2015-3246: Red Hat Libuser Race Condition Vulnerability

**Signal:** Exploited: patch now if you run it. CISA has confirmed exploitation in the wild. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Yes, if you run Red Hat Libuser. CISA added this CVE to its Known Exploited Vulnerabilities catalog on 2026-08-26, which means there is reliable evidence of exploitation in the wild. US federal agencies must remediate by 2026-09-09 ; treat that as the outer limit, not the target.
- EPSS 8.5% , percentile 95: FIRST’s model estimates a 8.5% chance of exploitation activity in the next 30 days, higher than 95% of all scored CVEs (very high). EPSS is a probability, not a verdict.
- Needs local access needed. Lower urgency for most teams unless an attacker could already run code on the machine.
- Editorial verdict: Most can relax. libuser CVE-2015-3246: 2015 Linux Root Bug Lands in KEV — Any RHEL or CentOS 6 or 7 host that has taken updates since July 2015 is already fixed; the real risk is forgotten legacy Linux servers, where this is one of several old root exploits attackers now chain after a web compromise.

## What it is

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 (CVE record)

- n/a n/a: see advisory

## Severity

- CISA-ADP CVSS 3.1: 7.4 `CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: added 2026-08-26; federal due date 2026-09-09. Known ransomware use: Unknown.
- CISA required action: 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.
- CISA SSVC assessment: exploitation active , automatable no , technical impact total .
- FIRST EPSS (model of 2026-10-21): 8.50% probability of exploitation activity in the next 30 days; percentile 95.

## Sources

- [FEDORA-2015-12301](http://lists.fedoraproject.org/pipermail/package-announce/2015-July/162947.html)
- [RHSA-2015:1482](http://rhn.redhat.com/errata/RHSA-2015-1482.html)
- [FEDORA-2015-12064](http://lists.fedoraproject.org/pipermail/package-announce/2015-August/163044.html)
- [openSUSE-SU-2015:1332](http://lists.opensuse.org/opensuse-security-announce/2015-08/msg00000.html)
- [RHSA-2015:1483](http://rhn.redhat.com/errata/RHSA-2015-1483.html)
- [Listed in CISA KEV notes (access.redhat.com)](https://access.redhat.com/articles/1537873)
- [CVE.org record CVE-2015-3246](https://www.cve.org/CVERecord?id=CVE-2015-3246)
- [NVD entry CVE-2015-3246](https://nvd.nist.gov/vuln/detail/CVE-2015-3246)
- [CISA Known Exploited Vulnerabilities catalog entry](https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2015-3246)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/bod-26-04-prioritizing-security-updates-based-risk)
- [Listed in CISA KEV notes (cisa.gov)](https://www.cisa.gov/news-events/directives/bod-26-04-implementation-guidance-prioritizing-security-updates-based-risk)
- [76022](http://www.securityfocus.com/bid/76022)
- [44633](https://www.exploit-db.com/exploits/44633/)
- [qualys.com](https://www.qualys.com/2015/07/23/cve-2015-3245-cve-2015-3246/cve-2015-3245-cve-2015-3246.txt)
- [1033040](http://www.securitytracker.com/id/1033040)
- [blog.talosintelligence.com](https://blog.talosintelligence.com/uat-10147-chinese-speaking-adversary-integrates-agentic-ai-into-post-compromise-operations/)

---
Source page: https://erroneo.us/security/cve/CVE-2015-3246/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt