CVE-2025-6020: Linux PAM Privilege Escalation Vulnerability

CVE-2025-6020 Overview

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.

Critical Impact
Local privilege escalation via symlink attacks

Affected Products

linux-pam (Specific versions not detailed)
Red Hat Enterprise Linux
Debian LTS

Discovery Timeline

Not Available - Vulnerability discovered by Not Available
Not Available - Responsible disclosure to Not Available
Not Available - CVE CVE-2025-6020 assigned
Not Available - Vendor releases security patch
2025-06-17 - CVE CVE-2025-6020 published to NVD
2025-11-06 - Last updated in NVD database

Technical Details for CVE-2025-6020

Vulnerability Analysis

The vulnerability arises due to pam_namespace in linux-pam improperly handling user-controlled paths. This flaw makes the system susceptible to symlink attacks that local attackers can exploit to escalate their privileges to root.

Root Cause

The root cause of the issue is improper validation and sanitization of user-controlled paths in the pam_namespace module.

Attack Vector

The attack vector is local, involving exploitation through symlink attacks and race conditions.

// Example exploitation code (sanitized)
#include <unistd.h>

int main() {
    symlink("/etc/shadow", "/tmp/fake_shadow");
    // Timing attack with suboptimal path control
    return 0;
}

Detection Methods for CVE-2025-6020

Indicators of Compromise

Unusual symlink creations in critical directories
Unexpected privilege escalations
Logs indicating unauthorized pam_namespace access

Detection Strategies

Implement file integrity monitoring on sensitive directories to detect anomalous symlink creation. Leverage system audit logs to trace unauthorized accesses or privilege changes involving pam_namespace.

Monitoring Recommendations

Constantly monitor system logs and use intrusion detection systems to alert administrators of potential exploitation attempts involving symlink manipulations.

How to Mitigate CVE-2025-6020

Immediate Actions Required

Disable pam_namespace if not required in your environment
Implement strict access controls on directories affected by symlink vulnerabilities
Regularly review and audit user permissions

Patch Information

Patch details are available through the vendor’s advisories. Please refer to RHSA-2025:15828 for patch information.

Workarounds

Ensure proper directory permissions are set to restrict symlink and file creation by unauthorized users. Consider using namespace support with enhanced security configurations.

bash

# Configuration example
chmod 750 /some/critical/directory
chown root:root /some/critical/directory