CVE-2025-11712
An OBJECT tag type attribute overrode browser behavior on web resources without a content-type
- State
- Published
- Severity
- 6.1 Medium
- Published
- Oct 14, 2025
- Updated
- Apr 13, 2026
- Reserved
- Oct 13, 2025
Description
A malicious page could have used the type attribute of an OBJECT tag to override the default browser behavior when encountering a web resource served without a content-type. This could have contributed to an XSS on a site that unsafely serves files without a content-type header. This vulnerability was fixed in Firefox 144, Firefox ESR 140.4, Thunderbird 144, and Thunderbird 140.4.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 6.1 Medium | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N | CISA-ADP |
Weaknesses
- CWE-116 Improper Encoding or Escaping of Output
Affected Products
| Product | Versions |
|---|---|
FirefoxMozilla |
|
ThunderbirdMozilla |
|
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=1979536
- https://www.mozilla.org/security/advisories/mfsa2025-81/
- https://www.mozilla.org/security/advisories/mfsa2025-83/
- https://www.mozilla.org/security/advisories/mfsa2025-84/
- https://www.mozilla.org/security/advisories/mfsa2025-85/
- https://lists.debian.org/debian-lts-announce/2025/10/msg00031.html
- https://lists.debian.org/debian-lts-announce/2025/10/msg00015.html
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