Description
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.
Affected products
mozilla: firefox
References7
- www.mozilla.org/security/advisories/mfsa2025-51/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2025-53/ Vendor Advisory
- bugzilla.mozilla.org/show_bug.cgi?id=1971140 Permissions Required
- www.mozilla.org/security/advisories/mfsa2025-54/
- www.mozilla.org/security/advisories/mfsa2025-55/
- lists.debian.org/debian-lts-announce/2025/06/msg00029.html
- lists.debian.org/debian-lts-announce/2025/07/msg00002.html
Metrics
- CVSS 3.1
-
6.1
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N - EPSS — exploit probability
- 0% percentile: 19 · as of 7 November 2026
- CWE
- CWE-79
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