Description
Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
Published: 2026-09-01
Score: 9.8 Critical
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
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-4770-1 firefox-esr security update
Debian DSA Debian DSA DSA-6481-1 firefox-esr security update
Debian DSA Debian DSA DSA-6483-1 thunderbird security update
History

Thu, 03 Sep 2026 20:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-787

Thu, 03 Sep 2026 18:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-200
Metrics ssvc

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


Thu, 03 Sep 2026 16:00:00 +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
Metrics 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'}


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

Type Values Removed Values Added
Description Internally found bugs present in Firefox 154, Firefox ESR 153.1 and Firefox ESR 140.14. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, and Firefox ESR 153.2. Internally found bugs present in Thunderbird 154, Thunderbird ESR 153.1 and Thunderbird ESR 140.14. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, Firefox ESR 153.2, Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
Title Internally found bugs fixed in Firefox 155, Firefox ESR 153.2 and Firefox ESR 140.15 Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15
References

Tue, 01 Sep 2026 14:15:00 +0000

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

Tue, 01 Sep 2026 14:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-119
CWE-787

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

Type Values Removed Values Added
Description Internally found bugs present in Firefox 154, Firefox ESR 153.1 and Firefox ESR 140.14. Some of these bugs showed evidence of memory corruption or another security-relevant defect and we presume that with enough effort some of these could have been exploited. This vulnerability was fixed in Firefox 155, Firefox ESR 140.15, and Firefox ESR 153.2.
Title Internally found bugs fixed in Firefox 155, Firefox ESR 153.2 and Firefox ESR 140.15
References

Subscriptions

Mozilla Firefox Thunderbird
cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published:

Updated: 2026-09-03T17:23:35.483Z

Reserved: 2026-09-01T07:26:01.305Z

Link: CVE-2026-84143

cve-icon Vulnrichment

Updated: 2026-09-03T17:17:24.835Z

cve-icon NVD

Status : Modified

Published: 2026-09-01T13:20:08.457

Modified: 2026-09-03T18:17:27.053

Link: CVE-2026-84143

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-09-03T21:45:09Z

Weaknesses