CVE-2026-2766
Critical · CVSS 9.8Firefox / Thunderbird JavaScript Engine JIT — Use-after-free in JIT compiler (JavaScript Engine)
- CVSS
- 9.8
- nvd
- EPSS
- —
- KEV
- No
- Class
- oss containerizable
- CWE-416, CWE-416
Description
Use-after-free in the JavaScript Engine: JIT component. This vulnerability was fixed in Firefox 148, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Search profile — drives PoC discovery
Symbols JITJavaScript Engineuse-after-freeSpiderMonkeyIonMonkeyJitCodeJSScriptJSContextbugzilla 2013583mfsa2026-13mfsa2026-15mfsa2026-16mfsa2026-17
Keywords CVE-2026-2766Firefox JIT use-after-freeSpiderMonkey use-after-freeFirefox 148 UAFFirefox ESR 140.8 exploitThunderbird JIT CVE-2026-2766Mozilla JIT RCEbugzilla 2013583 PoCmfsa2026-13 exploitFirefox JavaScript engine UAF PoC
Versions: Firefox < 148, Firefox ESR < 140.8, Thunderbird < 148, Thunderbird < 140.8
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2013583
- 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