# CVE-2015-3246: Red Hat Libuser race condition in passwd file handling

Source: https://junglewise.ai/threats/cve-2015-3246-red-hat-libuser-race-condition-in-passwd-file-handling  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-08-26. Updated: 2026-09-24  
License: CC BY 4.0 with a link back

CVE-2015-3246 · Severity: critical · Exploited in the wild · Published 2026-08-26

Red Hat libuser is a system library used to manage user and group accounts on Linux systems. A race condition in how it writes to the password database (/etc/passwd) allows local users with valid system access to cause service outages or gain elevated privileges through file corruption. This vulnerability has already been exploited by attackers in real-world scenarios.

Vendors: [Red Hat](https://junglewise.ai/threats/vendors/red-hat).

## Quick answers

**Is CVE-2015-3246 exploited in the wild?** Yes. CVE-2015-3246 is known to be exploited in the wild, first recorded on 26 August 2026. Treat it as urgent.

**How severe is CVE-2015-3246?** Critical severity, published 26 August 2026.

**Which products and versions are affected?** Red Hat Libuser <UNKNOWN>.

**Is there a fix for CVE-2015-3246?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2015-3246 attacked?** It is attacked with local access.

**Am I affected by CVE-2015-3246?** Check whether you run Red Hat Libuser at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The vulnerability is a race condition in Red Hat libuser's handling of the /etc/passwd file during user/group account modifications. An authenticated local attacker can exploit a time-of-check-time-of-use (TOCTOU) window in the file writing mechanism to corrupt critical password database entries. The attack requires local system access and can be triggered by performing rapid or concurrent account operations. Successful exploitation allows an attacker to deny service by corrupting password entries or escalate privileges by injecting malicious account data. The vulnerability has already been exploited in active attacks, indicating practical weaponization.

## Affected products

- Red Hat Libuser <UNKNOWN>

## Timeline

- 2026-08-26: disclosed
- exploited: Reported exploited in the wild