Firefox File Handling Mitigation Bypass (Before 150/ESR 140.10)
CVE-2026-6763 Published on April 21, 2026
Mitigation bypass in the File Handling component
Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox 150, Firefox ESR 140.10, Thunderbird 150, and Thunderbird 140.10.
Vulnerability Analysis
CVE-2026-6763 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality and integrity, and no impact on availability.
Weakness Type
Protection Mechanism Failure
The product does not use or incorrectly uses a protection mechanism that provides sufficient defense against directed attacks against the product. This weakness covers three distinct situations. A "missing" protection mechanism occurs when the application does not define any mechanism against a certain class of attack. An "insufficient" protection mechanism might provide some defenses - for example, against the most common attacks - but it does not protect against everything that is intended. Finally, an "ignored" mechanism occurs when a mechanism is available and in active use within the product, but the developer has not applied it in some code path.
Products Associated with CVE-2026-6763
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Affected Versions
Mozilla Firefox:- Version 140.10, <= 140.* is unaffected.
- Version 150, <= * is unaffected.
- Version 140.10, <= 140.* is unaffected.
- Version 150, <= * is unaffected.