CVE-2026-2771
criticalUndefined behavior in the DOM: Core & HTML component.
Vendor / product: Mozilla — firefox
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.
CVSS
9.8
9.8 (CVSS v3.1)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Severity source: NVD CVSS v3.1 (nvd@nist.gov)
Timeline (UTC)
Published: 2026-02-24 14:16
Modified: 2026-09-21 20:17
NVD status: Modified
Last synced 2 days ago
Verified against the source API 2026-10-27 07:07 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).
Affected products
mozilla / firefox <115.33.0, <148.0, ≥128.0 <140.8.0
mozilla / thunderbird <140.8.0, <148.0
Weakness classification (CWE)
NVD-CWE-noinfo CWE-125
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-13/
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-14/
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-15/
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-16/
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-17/
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2014593 security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-13/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-14/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-15/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-16/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-17/ security@mozilla.org
- https://access.redhat.com/errata/RHSA-2026:3338 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3339 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3361 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3491 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3492 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3493 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3494 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3495 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3496 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3497 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3515 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3516 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3517 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3976 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3978 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3979 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3980 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3981 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
- https://access.redhat.com/errata/RHSA-2026:3982 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
Data sources
NVD CVE API 2.0 — fetched 2026-10-27 07:07 UTC · record ↗