CVE-2025-1936: Mozilla Firefox

High severity, CVSS 7.3. EPSS: 0.4% chance of exploitation in the next 30 days.

jar: URLs retrieve local file content packaged in a ZIP archive. The null and everything after it was ignored when retrieving the content from the archive, but the fake extension after the null was used to determine the type of content. This could have been used to hide code in a web extension disguised as something else like an image. This vulnerability was fixed in Firefox 136, Firefox ESR 128.8, Thunderbird 136, and Thunderbird 128.8.

Affected products

• Mozilla Firefox: before 128.8.0 (fixed in 128.8.0); before 136.0 (fixed in 136.0)
• Mozilla Thunderbird: before 128.8.0 (fixed in 128.8.0); from 129.0, before 136.0 (fixed in 136.0)

Published 2025-03-04. Last modified 2026-10-05.