CVE-2025-6018 is a Local Privilege Escalation vulnerability discovered in the pam-config module of Linux Pluggable Authentication Modules (PAM). PAM is a widely used framework for authentication in Linux environments. The flaw arises from incorrect authorization logic that allows an unprivileged local attacker—such as a user logged in remotely via SSH—to escalate their privileges to those normally granted only to physically present users with the 'allow_active' attribute. This attribute controls access to Polkit actions, which are critical for managing system-wide configurations and services. By exploiting this vulnerability, an attacker can bypass intended restrictions and execute privileged Polkit actions, potentially altering system settings, managing services, or accessing sensitive data. The vulnerability has a CVSS 3.1 base score of 7.8, reflecting high impact on confidentiality, integrity, and availability, with low attack complexity and no requirement for user interaction. Although no public exploits are currently known, the vulnerability's nature and PAM's ubiquity make it a significant risk. The affected versions are not explicitly detailed but pertain to pam-config within PAM implementations. The vulnerability was reserved in June 2025 and published in July 2025, with Red Hat as the assigner. The flaw requires local access but can be triggered remotely via SSH sessions, increasing the attack surface. This vulnerability highlights the critical need for strict authorization checks within authentication modules and the potential risks of privilege escalation in Linux systems.

For European organizations, this vulnerability poses a substantial risk, especially for enterprises and service providers relying heavily on Linux servers for critical infrastructure, cloud services, and internal IT operations. Successful exploitation can lead to unauthorized administrative control over affected systems, enabling attackers to manipulate system configurations, disable security controls, or deploy persistent backdoors. This can result in data breaches, service disruptions, and compliance violations under regulations such as GDPR. Organizations with remote user access, including SSH, are particularly vulnerable, as attackers do not need physical access to exploit the flaw. The impact extends to sectors like finance, government, healthcare, and telecommunications, where Linux-based systems are prevalent and security requirements are stringent. Additionally, the ability to perform privileged Polkit actions can facilitate lateral movement and further compromise within corporate networks. The absence of known exploits currently provides a window for proactive mitigation, but the high severity necessitates urgent attention.

To mitigate CVE-2025-6018, organizations should first identify all Linux systems using vulnerable versions of pam-config within PAM. Immediate steps include applying vendor patches as soon as they become available; monitoring official Linux distribution security advisories (e.g., Red Hat, Debian, Ubuntu) is essential. In the absence of patches, organizations should restrict local user access and limit SSH access to trusted users only, employing strict access controls and multi-factor authentication. Reviewing and hardening Polkit policies to minimize the number of users with 'allow_active' privileges can reduce risk exposure. Employing host-based intrusion detection systems (HIDS) to monitor unusual privilege escalations and auditing PAM and Polkit logs can help detect exploitation attempts. Network segmentation and the principle of least privilege should be enforced to contain potential breaches. Additionally, organizations should conduct internal penetration testing to verify the effectiveness of mitigations and raise awareness among system administrators about this specific vulnerability.