Description
Mitigation bypass in the File Handling component. This vulnerability was fixed in Firefox 157.0.1 and Thunderbird 158.
Affected products
mozilla: firefox
References3
- www.mozilla.org/security/advisories/mfsa2026-104/ Vendor Advisory
- bugzilla.mozilla.org/show_bug.cgi?id=2067465 Permissions Required
- www.mozilla.org/security/advisories/mfsa2026-109/
Metrics
- CVSS 3.1
-
9.8
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 25 · as of 10 November 2026
- CWE
- CWE-693
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.