CVE-2026-2765
Critical · CVSS 9.8Mozilla Firefox / Thunderbird JavaScript Engine — Use-after-free in JavaScript Engine (CWE-416)
- CVSS
- 9.8
- nvd
- EPSS
- —
- KEV
- No
- Class
- oss containerizable
- CWE-416, CWE-416
Description
Use-after-free in the JavaScript Engine component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Search profile — drives PoC discovery
Symbols SpiderMonkeyJSEnginebugzilla.mozilla.org/show_bug.cgi?id=2013562mfsa2026-13mfsa2026-15mfsa2026-16mfsa2026-17CVE-2026-2765
Keywords CVE-2026-2765Firefox use-after-free JavaScript engineSpiderMonkey use-after-freeFirefox 148 UAFFirefox ESR 140.8 vulnerabilityThunderbird 148 use-after-freemfsa2026-13bugzilla 2013562Mozilla JavaScript engine UAF PoC
Versions: Firefox < 148, Firefox ESR < 140.8, Thunderbird < 148, Thunderbird ESR < 140.8
Ranked PoCs (2) — best first
Heuristic ranking — not yet expert-vetted. Scored on structure + provenance, not execution.
- ★ 6
- ★ 0dead-lamer/CVE-2026-27654 needs reviewgh_search
Recall-favoring discovery; ranking by the Stage-4 scorer (Adam's rubric). Scanner/aggregator repos are hidden.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2013562
- https://www.mozilla.org/security/advisories/mfsa2026-13/
- https://www.mozilla.org/security/advisories/mfsa2026-15/
- https://www.mozilla.org/security/advisories/mfsa2026-16/
- https://www.mozilla.org/security/advisories/mfsa2026-17/
- https://access.redhat.com/errata/RHSA-2026:3338
- https://access.redhat.com/errata/RHSA-2026:3339
- https://access.redhat.com/errata/RHSA-2026:3361
- https://access.redhat.com/errata/RHSA-2026:3491
- https://access.redhat.com/errata/RHSA-2026:3492
- https://access.redhat.com/errata/RHSA-2026:3493
- https://access.redhat.com/errata/RHSA-2026:3494
Status: enriched · ingested 2026-06-30T06:00:22.000Z · profiled 2026-07-01T00:30:14.000Z