Description
Use-after-free in the DOM: Core & HTML component. This vulnerability was fixed in Firefox 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.
Affected products
mozilla: firefox; mozilla: thunderbird
References7
- www.mozilla.org/security/advisories/mfsa2026-74/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-76/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-77/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-78/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-79/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-80/ Vendor Advisory
- bugzilla.mozilla.org/show_bug.cgi?id=2057778 Permissions Required
Metrics
- CVSS 3.1
-
9.8
CRITICAL
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 0% percentile: 35 · as of 11 November 2026
- CWE
- CWE-416
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.