CVE-2025-11712

thunderbird: firefox: An OBJECT tag type attribute overrode browser behavior on web resources without a content-type

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Severity

Moderate

Red Hat Product Security

6.1

CVSS 3.1

Review impact separately from score.

Published · October 14, 2025

Updated · June 30, 2026

Description

A flaw was found in Thunderbird and Firefox. The Mozilla Foundation's Security Advisory describes the following issue: 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.

Statement

Red Hat Product Security rates the severity of this flaw as determined by the Mozilla Foundation Security Advisory.

CVSS score applicability

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.

Mitigation

No mitigation is specified in collected source.

CVSS / CWE

CVSS 3.1 · 6.1
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CWE-436 · Interpretation Conflict