Stefan Hornburg

**Name of the Vulnerable Software and Affected Versions** Courier MTA versions prior to 0.53.2 **Description** The issue allows attackers to cause a denial of service, specifically CPU consumption, by exploiting how usernames with the "=" character are handled during encoding. **Recommendations** For versions prior to 0.53.2, update to version 0.53.2 or later to resolve the issue.