An issue was discovered in Mailman Core before 3.3.5. An attacker with access to the REST API could use timing attacks to determine the value of the configured REST API password and then make arbitrary REST API calls. The REST API is bound to localhost by default, limiting the ability for attackers to exploit this, but can optionally be made to listen on other interfaces.

Pipermail in Mailman stores private mail messages with predictable filenames in a world-executable directory, which allows local users to read private mailing list archives.

Cross-site scripting vulnerability in Mailman email archiver before 2.08 allows attackers to obtain sensitive information or authentication credentials via a malicious link that is accessed by other web users.