CVE-2025-8031: Mozilla Firefox

Critical severity, CVSS 9.8. EPSS: 0.5% chance of exploitation in the next 30 days.

The `username:password` part was not correctly stripped from URLs in CSP reports potentially leaking HTTP Basic Authentication credentials. This vulnerability was fixed in Firefox 141, Firefox ESR 128.13, Firefox ESR 140.1, Thunderbird 141, Thunderbird 128.13, and Thunderbird 140.1.

Affected products

• Mozilla Firefox: before 128.13.0 (fixed in 128.13.0); before 141.0 (fixed in 141.0); from 140.0, before 140.1.0 (fixed in 140.1.0)
• Mozilla Thunderbird: before 128.13.0 (fixed in 128.13.0); before 141.0 (fixed in 141.0); from 140.0, before 140.1.0 (fixed in 140.1.0)

Published 2025-07-22. Last modified 2026-10-05.