CVE-2024-22365 is a vulnerability identified in Linux PAM (Pluggable Authentication Modules) versions prior to 1.6.0. The flaw stems from the improper use of the openat system call within the protect_dir function, where the O_DIRECTORY flag is omitted. This omission allows an attacker with local access and limited privileges to exploit the vulnerability by creating a named pipe (FIFO) using mkfifo in a directory expected to be protected. Because openat does not enforce directory semantics without O_DIRECTORY, the attacker can cause the authentication process to block indefinitely, effectively causing a denial of service (DoS) by preventing legitimate login attempts. The vulnerability affects the availability of authentication services but does not compromise confidentiality or integrity. Exploitation requires local privileges but no user interaction, and the attack surface is limited to systems running vulnerable Linux PAM versions. No known exploits are currently in the wild, and no official patches have been linked yet, though upgrading to Linux PAM 1.6.0 or later is expected to resolve the issue. The vulnerability is classified under CWE-664 (Improper Control of a Resource Through its Lifetime), highlighting the improper handling of file descriptors and directory protections.

For European organizations, this vulnerability primarily threatens the availability of authentication services on Linux-based systems. Since Linux PAM is widely used for managing authentication on servers and workstations, exploitation could lead to denial of service conditions, blocking user logins and potentially disrupting critical business operations, especially in environments relying on automated or remote authentication. Sectors such as finance, healthcare, government, and critical infrastructure that depend on Linux servers for identity and access management could experience operational downtime. While the vulnerability does not expose sensitive data or allow privilege escalation, the inability to authenticate users can halt workflows and services, leading to productivity losses and potential compliance issues. The requirement for local access limits remote exploitation, but insider threats or compromised accounts could leverage this flaw. The absence of known exploits reduces immediate risk, but the medium CVSS score indicates a need for timely remediation to prevent future attacks.

To mitigate CVE-2024-22365, organizations should prioritize upgrading Linux PAM to version 1.6.0 or later once official patches are released. In the interim, restrict local user permissions to prevent the creation of named pipes or special files in directories used by PAM for authentication processes. Implement strict file system permissions and monitoring to detect unusual FIFO creation attempts. Employ host-based intrusion detection systems (HIDS) to alert on suspicious local activities involving mkfifo or openat system calls. Additionally, consider isolating critical authentication servers and limiting local user access to reduce the attack surface. Regularly audit PAM configurations and logs to identify anomalies. Coordinate with Linux distribution vendors for timely patch deployment and verify updates through testing before production rollout. Finally, educate system administrators about this vulnerability and encourage proactive system hardening practices.