Description
Mitigation bypass in the DOM: HTML Parser component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.
Published: 2026-02-24
Score: 9.8 Critical
EPSS: < 1% Very Low
KEV: No
Impact: Security mitigation bypass (CWE-288) in the HTML parser of Mozilla Firefox and Thunderbird
Action: Immediate Patch
AI Analysis

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Remediation

No vendor fix or workaround currently provided.

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Tracking

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4495-1 thunderbird security update
Debian DLA Debian DLA DLA-4496-1 firefox-esr security update
Debian DSA Debian DSA DSA-6148-1 firefox-esr security update
Debian DSA Debian DSA DSA-6152-1 thunderbird security update
References
Link Providers
https://access.redhat.com/errata/RHSA-2026:3338 cve-icon
https://access.redhat.com/errata/RHSA-2026:3339 cve-icon
https://access.redhat.com/errata/RHSA-2026:3361 cve-icon
https://access.redhat.com/errata/RHSA-2026:3491 cve-icon
https://access.redhat.com/errata/RHSA-2026:3492 cve-icon
https://access.redhat.com/errata/RHSA-2026:3493 cve-icon
https://access.redhat.com/errata/RHSA-2026:3494 cve-icon
https://access.redhat.com/errata/RHSA-2026:3495 cve-icon
https://access.redhat.com/errata/RHSA-2026:3496 cve-icon
https://access.redhat.com/errata/RHSA-2026:3497 cve-icon
https://access.redhat.com/errata/RHSA-2026:3515 cve-icon
https://access.redhat.com/errata/RHSA-2026:3516 cve-icon
https://access.redhat.com/errata/RHSA-2026:3517 cve-icon
https://access.redhat.com/errata/RHSA-2026:3976 cve-icon
https://access.redhat.com/errata/RHSA-2026:3978 cve-icon
https://access.redhat.com/errata/RHSA-2026:3979 cve-icon
https://access.redhat.com/errata/RHSA-2026:3980 cve-icon
https://access.redhat.com/errata/RHSA-2026:3981 cve-icon
https://access.redhat.com/errata/RHSA-2026:3982 cve-icon
https://access.redhat.com/errata/RHSA-2026:3983 cve-icon
https://access.redhat.com/errata/RHSA-2026:3984 cve-icon
https://access.redhat.com/errata/RHSA-2026:4022 cve-icon
https://access.redhat.com/errata/RHSA-2026:4152 cve-icon
https://access.redhat.com/errata/RHSA-2026:4260 cve-icon
https://access.redhat.com/errata/RHSA-2026:4432 cve-icon
https://access.redhat.com/security/cve/CVE-2026-2775 cve-icon
https://bugzilla.mozilla.org/show_bug.cgi?id=2015199 cve-icon cve-icon
https://bugzilla.redhat.com/show_bug.cgi?id=2442314 cve-icon
https://nvd.nist.gov/vuln/detail/CVE-2026-2775 cve-icon
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-2775.json cve-icon
https://www.cve.org/CVERecord?id=CVE-2026-2775 cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-13/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-14/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-15/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-15/#CVE-2026-2775 cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-16/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-17/ cve-icon cve-icon
History

Mon, 13 Apr 2026 14:30:00 +0000

Type Values Removed Values Added
Description Mitigation bypass in the DOM: HTML Parser component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8. Mitigation bypass in the DOM: HTML Parser component. This vulnerability was fixed in Firefox 148, Firefox ESR 115.33, Firefox ESR 140.8, Thunderbird 148, and Thunderbird 140.8.

Mon, 02 Mar 2026 02:15:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}


Sat, 28 Feb 2026 04:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-288

Wed, 25 Feb 2026 16:30:00 +0000

Type Values Removed Values Added
Weaknesses NVD-CWE-noinfo
CPEs cpe:2.3:a:mozilla:firefox:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:esr:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:-:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}

cvssV3_1

{'score': 9.8, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H'}


Wed, 25 Feb 2026 12:00:00 +0000

Type Values Removed Values Added
First Time appeared Mozilla
Mozilla firefox
Mozilla firefox Esr
Mozilla thunderbird
Vendors & Products Mozilla
Mozilla firefox
Mozilla firefox Esr
Mozilla thunderbird

Wed, 25 Feb 2026 00:15:00 +0000

Type Values Removed Values Added
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H'}

threat_severity

Important


Tue, 24 Feb 2026 18:00:00 +0000

Type Values Removed Values Added
Description Mitigation bypass in the DOM: HTML Parser component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8. Mitigation bypass in the DOM: HTML Parser component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, Firefox ESR < 140.8, Thunderbird < 148, and Thunderbird < 140.8.
References

Tue, 24 Feb 2026 14:00:00 +0000

Type Values Removed Values Added
Description Mitigation bypass in the DOM: HTML Parser component. This vulnerability affects Firefox < 148, Firefox ESR < 115.33, and Firefox ESR < 140.8.
Title Mitigation bypass in the DOM: HTML Parser component
References

Subscriptions

Mozilla Firefox Firefox Esr Thunderbird
cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published:

Updated: 2026-07-15T01:13:08.259Z

Reserved: 2026-02-19T15:05:58.825Z

Link: CVE-2026-2775

cve-icon Vulnrichment

Updated: 2026-02-28T03:21:25.726Z

cve-icon NVD

Status : Modified

Published: 2026-02-24T14:16:25.917

Modified: 2026-07-15T02:19:39.927

Link: CVE-2026-2775

cve-icon Redhat

Severity : Important

Publid Date: 2026-02-24T13:33:11Z

Links: CVE-2026-2775 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-04-15T17:15:10Z

Weaknesses