CVE-2025-6018 is a Local Privilege Escalation (LPE) vulnerability discovered in the pam-config module within Linux Pluggable Authentication Modules (PAM). PAM is a widely used framework for authentication on Linux systems, managing user credentials and access controls. The vulnerability arises due to incorrect authorization logic in pam-config that improperly grants elevated privileges to unprivileged local users. Specifically, an attacker who has local access—such as via an SSH session—can exploit this flaw to gain the privileges associated with a physically present user granted 'allow_active' status in Polkit. Polkit is a system service used to define and enforce policies for system-wide privileges, typically restricting sensitive actions to console users. By bypassing these restrictions, the attacker can perform privileged operations normally disallowed to remote or non-console users, including modifying system configurations, managing services, or other sensitive tasks. The vulnerability does not require user interaction and has a low attack complexity, but it does require local access and some privileges (local user). The CVSS v3.1 base score is 7.8, reflecting high impact on confidentiality, integrity, and availability. No public exploits have been reported yet, but the flaw's nature makes it a critical concern for Linux environments, especially multi-user systems and servers accessible via SSH. The vulnerability affects all versions of pam-config as indicated, and no official patches or mitigations have been linked yet. The flaw was reserved in June 2025 and published in July 2025, indicating recent discovery and disclosure.

The impact of CVE-2025-6018 is significant for organizations running Linux systems that utilize PAM and Polkit for authentication and privilege management. An attacker exploiting this vulnerability can escalate from a low-privileged local user to effectively a console user with broad Polkit permissions. This can lead to unauthorized changes in system configurations, service management, installation or removal of software, and potentially full system compromise. Confidentiality is at risk as attackers may access sensitive data or credentials. Integrity is compromised through unauthorized modifications to system settings and files. Availability could be affected if attackers disrupt critical services or configurations. The vulnerability is particularly dangerous in environments where multiple users have SSH access, such as shared hosting, enterprise servers, or cloud instances. It increases the attack surface by allowing remote-like users to gain local console privileges without physical presence. Although no exploits are known in the wild yet, the vulnerability's characteristics make it a prime target for attackers seeking persistent and privileged access. Organizations with strict compliance requirements or critical infrastructure may face regulatory and operational risks if exploited.

1. Immediately restrict local user access to trusted personnel only, especially limiting SSH access to essential users. 2. Monitor and audit local user activities and Polkit actions to detect unusual privilege escalations or unauthorized commands. 3. Implement strict SSH access controls, including multi-factor authentication and IP whitelisting, to reduce the risk of unauthorized local access. 4. Use Linux security modules (e.g., SELinux, AppArmor) to enforce additional access controls around PAM and Polkit components. 5. Apply any official patches or updates to pam-config and PAM modules as soon as they become available from Linux distribution vendors. 6. Consider temporary workarounds such as disabling or restricting 'allow_active' Polkit actions for non-console users until a patch is deployed. 7. Employ host-based intrusion detection systems (HIDS) to alert on suspicious privilege escalation attempts. 8. Educate system administrators about this vulnerability to ensure rapid response and mitigation. 9. Review and harden PAM and Polkit configurations to minimize unnecessary privileges and reduce attack surface. 10. Maintain up-to-date backups and incident response plans to recover quickly if exploitation occurs.