Exim Out-of-Bounds Write Vulnerability in SPA Authentication Driver

A vulnerability in Exim versions prior to 4.99.2 allows for an out-of-bounds write when the SPA authentication driver is used with a malicious SPA resource. This can lead to a crash of the connection instance or cause erroneous data processing that exposes information from uninitialized heap memory.

Impact

Exploitation of this vulnerability can cause a remote-triggered crash of the connection process, not the daemon, and may result in unauthorized information disclosure from heap memory.

Remediation

Users can upgrade to Exim version 4.99.2, available as a tarball from the Exim FTP site or directly from Git. Instructions for verifying the release signature are also provided.