CVE-2025-6018 in pam-config
Summary
by MITRE • 07/23/2025
A Local Privilege Escalation (LPE) vulnerability has been discovered in pam-config within Linux Pluggable Authentication Modules (PAM). This flaw allows an unprivileged local attacker (for example, a user logged in via SSH) to obtain the elevated privileges normally reserved for a physically present, "allow_active" user. The highest risk is that the attacker can then perform all allow_active yes Polkit actions, which are typically restricted to console users, potentially gaining unauthorized control over system configurations, services, or other sensitive operations.
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Analysis
by VulDB Data Team • 10/09/2025
The vulnerability CVE-2025-6018 represents a critical local privilege escalation flaw within the pam-config component of Linux Pluggable Authentication Modules (PAM) framework. This issue specifically targets the authentication and authorization mechanisms that govern user access rights on Linux systems, creating a dangerous pathway for unprivileged users to bypass normal security controls. The flaw exists in how pam-config handles user session management and privilege delegation, allowing attackers to exploit a design weakness that should normally restrict certain high-privilege operations to physically present users only.
The technical implementation of this vulnerability stems from improper validation of user authentication contexts within the PAM module architecture. When a user establishes a session through SSH or other non-physical means, the pam-config module fails to properly enforce the "allow_active" restriction that typically prevents remote users from executing commands that require physical presence. This misconfiguration creates a privilege escalation vector where an attacker can manipulate the session context to gain elevated privileges that should only be available to console users. The vulnerability operates at the kernel level within the PAM subsystem, making it particularly dangerous as it can be exploited without requiring specialized tools or extensive system knowledge.
The operational impact of CVE-2025-6018 extends far beyond simple privilege escalation, as it enables attackers to perform all actions that are typically restricted to physically present users with "allow_active yes" Polkit configurations. This includes unauthorized modification of system configurations, manipulation of critical services, and access to sensitive data that should remain protected from remote exploitation. The vulnerability essentially allows an attacker to circumvent the fundamental security principle that separates remote and local user privileges, potentially enabling complete system compromise. Attackers can leverage this flaw to install malicious software, modify system binaries, or establish persistent backdoors that persist across reboots.
Security professionals should implement immediate mitigations including updating pam-config to versions that address this vulnerability, reviewing and tightening Polkit configurations to minimize the scope of allow_active permissions, and implementing monitoring solutions that can detect unusual privilege escalation attempts. The vulnerability aligns with CWE-284, which describes improper access control mechanisms, and maps to ATT&CK technique T1068, involving local privilege escalation through system configuration flaws. Organizations should also consider implementing additional security controls such as mandatory access controls, privilege separation mechanisms, and regular security audits to detect potential exploitation attempts. The remediation process requires careful attention to ensure that legitimate system administration operations continue to function properly while closing the security gap that enables this unauthorized privilege escalation.