CVE-2026-72694

A flaw was found in MRTG. When the MRTG daemon is started as a root user and subsequently drops privileges, a local, low-privileged attacker can exploit a symbolic link (symlink) following vulnerability. By influencing or pre-placing a symlink in the process ID (PID) file path, the attacker can trick the root process into changing the ownership of an arbitrary existing file to the daemon user. This can lead to local privilege escalation, allowing unauthorized access to or modification of sensitive files.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

To mitigate this issue, avoid starting the MRTG daemon as root with the --daemon option. Instead, configure MRTG to run directly as an unprivileged user. If root startup is strictly necessary, ensure that the PID file and its directory are owned by root and are not writable by unprivileged users, and prevent untrusted users from influencing the --pid-file path. Changes to service configuration may require a service restart to take effect.