When a file download is specified via the `Content-Disposition` header, that directive would be ignored if the file was included via a `<embed>` or `<object>` tag, potentially making a website vulnerable to a cross-site scripting attack. This vulnerability was fixed in Firefox 140, Firefox ESR 128.12, Thunderbird 140, and Thunderbird 128.12.
Fix
Patch, vendor advisory and mitigation references on NVD 2
- https://www.mozilla.org/security/advisories/mfsa2025-51/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-53/ Vendor Advisory
Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.
Change history 1
- First seenCVSS 6.1 · mozillaNVD modified 2026-10-23 22:10
Affected (CPE criteria) 2
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
References 7
- https://bugzilla.mozilla.org/show_bug.cgi?id=1971140 Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2025-51/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-53/ Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2025-54/
- https://www.mozilla.org/security/advisories/mfsa2025-55/
- https://lists.debian.org/debian-lts-announce/2025/06/msg00029.html
- https://lists.debian.org/debian-lts-announce/2025/07/msg00002.html