CVE-2020-12137

Name of the Vulnerable Software and Affected Versions GNU Mailman versions 2.x through 2.1.29 GNU Mailman version 2.1.30 is not affected, but all versions prior to 2.1.30 are vulnerable.

Description The issue is related to the handling of MIME parts in GNU Mailman, which may contribute to cross-site scripting (XSS) attacks against visitors of list archives. This occurs because an HTTP reply from an archive web server may lack a MIME type, leading a web browser to perform MIME sniffing and potentially execute JavaScript code. The vulnerability is also related to the lack of protection for the web page structure, which could allow a remote attacker to impact data integrity.

Recommendations For GNU Mailman versions 2.x through 2.1.29, update to version 2.1.30 or later to resolve the issue. As a temporary workaround, consider restricting access to list archives to minimize the risk of exploitation.