CVE-2026-2763
Critical · CVSS 9.8Mozilla Firefox / Thunderbird JavaScript Engine — Use-after-free in JavaScript Engine (SpiderMonkey)
- 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 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Search profile — drives PoC discovery
Symbols SpiderMonkeyJSEnginejs::gcJSObjectfinalizeGCRuntimeZone::sweepJSScriptNativeObjectbugzilla.mozilla.org/show_bug.cgi?id=2012018mfsa2026-13mfsa2026-14mfsa2026-15mfsa2026-16
Keywords CVE-2026-2763Firefox use-after-free JavaScript engineSpiderMonkey UAF CVE-2026-2763Firefox 148 use-after-free PoCMozilla mfsa2026-13 exploitMozilla mfsa2026-14 exploitFirefox ESR 140.8 UAFThunderbird JavaScript engine use-after-freebugzilla 2012018 PoCCWE-416 Firefox SpiderMonkey
Versions: Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, Thunderbird < 140.8
Ranked PoCs (3) — best first
Heuristic ranking — not yet expert-vetted. Scored on structure + provenance, not execution.
- ★ 1
- ★ 2
- ★ 1
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=2012018
- https://www.mozilla.org/security/advisories/mfsa2026-13/
- https://www.mozilla.org/security/advisories/mfsa2026-14/
- 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
Status: enriched · ingested 2026-06-30T06:00:22.000Z · profiled 2026-07-01T00:30:14.000Z