GNU Mailman 2.x before 2.1.30 uses the .obj extension for scrubbed application/octet-stream MIME parts. This behavior may contribute to XSS attacks against list-archive visitors, because an HTTP reply from an archive web server may lack a MIME type, and a web browser may perform MIME sniffing, conclude that the MIME type should have been text/html, and execute JavaScript code.
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.