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.

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Firefox Esr Subscribe
Thunderbird Subscribe
Advisories
Source ID Title
Debian DLA Debian DLA DLA-4335-1 firefox-esr security update
Debian DLA Debian DLA DLA-4351-1 thunderbird security update
Debian DSA Debian DSA DSA-6025-1 firefox-esr security update
Debian DSA Debian DSA DSA-6040-1 thunderbird security update
Ubuntu USN Ubuntu USN USN-7991-1 Thunderbird vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Mon, 13 Apr 2026 15:00:00 +0000

Type Values Removed Values Added
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 affects Firefox < 144, Firefox ESR < 140.4, Thunderbird < 144, and Thunderbird < 140.4. 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.

Mon, 03 Nov 2025 18:30:00 +0000


Thu, 30 Oct 2025 16:30:00 +0000

Type Values Removed Values Added
Title thunderbird: firefox: An OBJECT tag type attribute overrode browser behavior on web resources without a content-type An OBJECT tag type attribute overrode browser behavior on web resources without a content-type

Mon, 20 Oct 2025 16:00:00 +0000

Type Values Removed Values Added
First Time appeared Mozilla firefox Esr
Vendors & Products Mozilla firefox Esr

Fri, 17 Oct 2025 13:00:00 +0000

Type Values Removed Values Added
First Time appeared Mozilla
Mozilla firefox
Mozilla thunderbird
CPEs cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
Vendors & Products Mozilla
Mozilla firefox
Mozilla thunderbird

Wed, 15 Oct 2025 14:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-116
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Wed, 15 Oct 2025 12:30:00 +0000

Type Values Removed Values Added
Title thunderbird: firefox: An OBJECT tag type attribute overrode browser behavior on web resources without a content-type
Weaknesses CWE-436
References
Metrics threat_severity

None

cvssV3_1

{'score': 6.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'}

threat_severity

Moderate


Tue, 14 Oct 2025 13:00:00 +0000

Type Values Removed Values Added
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 affects Firefox < 144, Firefox ESR < 140.4, Thunderbird < 144, and Thunderbird < 140.4.
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published:

Updated: 2026-04-13T14:29:40.795Z

Reserved: 2025-10-13T19:50:07.919Z

Link: CVE-2025-11712

cve-icon Vulnrichment

Updated: 2025-11-03T17:31:51.952Z

cve-icon NVD

Status : Modified

Published: 2025-10-14T13:15:37.447

Modified: 2026-04-13T15:16:39.987

Link: CVE-2025-11712

cve-icon Redhat

Severity : Moderate

Publid Date: 2025-10-14T12:27:35Z

Links: CVE-2025-11712 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2025-10-20T15:49:35Z

Weaknesses