High [CVE-2025-6020] linux-pam directory traversal

A flaw was found in linux-pam. The module pam_namespace may use access user-controlled paths without proper protection, allowing local users to elevate their privileges to root via multiple symlink attacks and race conditions.

This vulnerability in pam_namespace marked as Important rather than Moderate due to its direct impact on privilege boundaries and the ease of exploitation in common configurations.

By leveraging symlink attacks or race conditions in polyinstantiated directories under their control, unprivileged local users can escalate to root, compromising the entire system.

Since pam_namespace is often used in multi-user environments (e.g., shared systems, terminal servers, containers), a misconfigured or partially protected setup becomes a single point of failure. The attack does not require special capabilities or kernel-level exploits—just timing and control over certain paths—making it both reliable and low-barrier.

Moreover, privilege escalation flaws like this can be chained with other vulnerabilities to persist or evade detection, further amplifying the risk. Red Hat severity: Important — CVSS 7.8 (CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H).

Weakness: CWE-22.