CVE-2020-12137: Canonical Ubuntu Linux

Medium severity, CVSS 6.1. EPSS: 2.3% chance of exploitation in the next 30 days.

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.

Affected products

• Canonical Ubuntu Linux: version 16.04 only; version 18.04 only
• Debian Debian Linux: version 9.0 only; version 10.0 only; version 8.0 only
• Fedoraproject Fedora: version 31 only; version 32 only
• GNU Mailman: from 2.0, before 2.1.30 (fixed in 2.1.30)
• Opensuse Backports Sle: version 15.0 only
• Opensuse Leap: version 15.2 only

Published 2020-04-24. Last modified 2026-06-17.