A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID response. Heap contents can ultimately be persisted to prefs.js. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.

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Advisories
Source ID Title
Debian DLA Debian DLA DLA-4775-1 thunderbird security update
Debian DSA Debian DSA DSA-6483-1 thunderbird security update
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Thu, 03 Sep 2026 19:15:00 +0000

Type Values Removed Values Added
CPEs cpe:2.3:a:mozilla:thunderbird:*:*:*:*:*:*:*:*

Thu, 03 Sep 2026 08:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

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


Wed, 02 Sep 2026 19:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416
Metrics cvssV3_1

{'score': 8.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:H'}

cvssV3_1

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


Wed, 02 Sep 2026 05:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416

Wed, 02 Sep 2026 00:30:00 +0000

Type Values Removed Values Added
Weaknesses CWE-416

Wed, 02 Sep 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-825
References
Metrics threat_severity

None

cvssV3_1

{'score': 8.3, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:H'}

threat_severity

Important


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

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

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

Type Values Removed Values Added
Description A malicious IMAP server can trigger use-after-free and heap-memory disclosure by sending a crafted ID response. Heap contents can ultimately be persisted to prefs.js. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2.
Title Information disclosure due to malicious IMAP server response
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: mozilla

Published:

Updated: 2026-09-02T18:47:17.033Z

Reserved: 2026-09-01T21:33:07.129Z

Link: CVE-2026-84641

cve-icon Vulnrichment

Updated: 2026-09-02T18:45:37.542Z

cve-icon NVD

Status : Analyzed

Published: 2026-09-01T22:17:19.900

Modified: 2026-09-03T19:01:11.823

Link: CVE-2026-84641

cve-icon Redhat

Severity : Important

Publid Date: 2026-09-01T21:33:07Z

Links: CVE-2026-84641 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-03T11:45:03Z

Weaknesses