CVE-2025-6430

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.

PUBLISHED Reserved 2025-06-20 | Published 2025-06-24 | Updated 2026-04-13 | Assigner mozilla

Product status

Credits

Daniil Satyaev (Positive Technologies)

References

lists.debian.org/debian-lts-announce/2025/07/msg00002.html

lists.debian.org/debian-lts-announce/2025/06/msg00029.html

bugzilla.mozilla.org/show_bug.cgi?id=1971140

www.mozilla.org/security/advisories/mfsa2025-51/

www.mozilla.org/security/advisories/mfsa2025-53/

www.mozilla.org/security/advisories/mfsa2025-54/

www.mozilla.org/security/advisories/mfsa2025-55/

cve.org (CVE-2025-6430)

nvd.nist.gov (CVE-2025-6430)

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