CVE-2026-2771
Critical · CVSS 9.8Mozilla Firefox / Thunderbird — Out-of-bounds read / Undefined behavior in DOM Core & HTML component (CWE-125)
- CVSS
- 9.8
- nvd
- EPSS
- —
- KEV
- No
- Class
- oss containerizable
- NVD-CWE-noinfo, CWE-125
Description
Undefined behavior in the DOM: Core & HTML 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 DOM CoreDOM HTMLmfsa2026-13mfsa2026-14mfsa2026-15mfsa2026-16bug 2014593
Keywords CVE-2026-2771Firefox 148Firefox ESR 115.33Firefox ESR 140.8Thunderbird 148Thunderbird 140.8DOM undefined behaviorout-of-bounds read Firefoxmfsa2026-13Mozilla DOM HTML CVE-2026-2771 PoC
Versions: Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, Thunderbird < 140.8
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2014593
- 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