Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

Metrics

No CVSS v4.0

Attack Vector Network

Attack Complexity Low

Privileges Required None

Scope Changed

Confidentiality Impact High

Integrity Impact High

Availability Impact High

User Interaction Required

No CVSS v3.0

No CVSS v2

This CVE is not in the KEV list.

Exploitation none

Automatable no

Technical Impact total

Affected Vendors & Products

Vendors Products
Mozilla
  • Firefox
  • Thunderbird

Configuration 1 [-]

OR cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

No data.

References
Link Providers
https://bugzilla.mozilla.org/show_bug.cgi?id=2059018 cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-82/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-83/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-84/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-85/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-86/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-87/ cve-icon cve-icon
https://www.mozilla.org/security/advisories/mfsa2026-88/ cve-icon cve-icon
History

Wed, 02 Sep 2026 16:45:00 +0000

Type Values Removed Values Added
First Time appeared Mozilla thunderbird
CPEs cpe:2.3:a:mozilla:firefox:*:*:*:*:*:*:*:*
cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*
Vendors & Products Mozilla thunderbird

Tue, 01 Sep 2026 22:00:00 +0000

Type Values Removed Values Added
Description Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2. Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
References

Tue, 01 Sep 2026 15:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416
Metrics cvssV3_1

{'score': 9.6, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H'}

ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'total'}, 'version': '2.0.3'}

Tue, 01 Sep 2026 13:45:00 +0000

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

Tue, 01 Sep 2026 12:45:00 +0000

Type Values Removed Values Added
Description Sandbox escape due to use-after-free in the DOM: Security component. This vulnerability was fixed in Firefox 155, Firefox ESR 115.40, Firefox ESR 140.15, and Firefox ESR 153.2.
Title Sandbox escape due to use-after-free in the DOM: Security component
References
cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published: 2026-09-01T12:18:41.535Z

Updated: 2026-09-02T03:55:38.279Z

Reserved: 2026-09-01T07:25:11.012Z

Link: CVE-2026-84121

cve-icon Vulnrichment

Updated: 2026-09-01T14:33:28.340Z

cve-icon NVD

Status : Analyzed

Published: 2026-09-01T13:20:05.933

Modified: 2026-09-02T16:36:20.367

Link: CVE-2026-84121

cve-icon Redhat

No data.