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CVE-2026-74987 Details

Description

Internally found bugs present in Thunderbird ESR 140.13, Thunderbird ESR 153.0 and Thunderbird 153. 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 154, Firefox ESR 140.14, Firefox ESR 153.1, Thunderbird 154, Thunderbird 140.14, and Thunderbird 153.1.

Metrics

CVSS 3.x Severity and Vector Strings:

CNA: CISA-ADPCVSS-B:9.8 CRITICALVector:CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

References to Advisories, Solutions, and Tools

By selecting these links, you will be leaving this site. These are references gathered from the official CVE record and are not endorsed by Volerion.

URL	Source(s)	Tag(s)
https://bugzilla.mozilla.org/buglist.cgi?bug_id=1500946%2C1788109%2C2045379%2C2045380%2C2049339%2C2049393%2C2053580%2C2054662%2C2054665%2C2054673%2C2054785%2C2058645	[email protected]	Broken Link
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2048797%2C2050536%2C2053272%2C2053579%2C2057115%2C2057116%2C2057130%2C2057991%2C2057995%2C2058002%2C2058008%2C2058032%2C2058102%2C2058667	[email protected]	Broken Link
https://bugzilla.mozilla.org/show_bug.cgi?id=2059424	[email protected]	Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-74/	[email protected]	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-76/	[email protected]	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-77/	[email protected]	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-78/	[email protected]	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-79/	[email protected]	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-80/	[email protected]	Vendor Advisory

see all 9 references

Weakness Enumeration

CWE-ID	CWE Name	Source
CWE-119	Improper Restriction of Operations within the Bounds of a Memory Buffer	CISA-ADP

Affected Products

Product	Versions
mozilla firefox	< 140.14.0 >= 141.0, < 153.1.0
CPE cpe:2.3:a:mozilla:firefox:::::::: Remediation No remediation found in references.
mozilla thunderbird	< 140.14.0 >= 141.0, < 153.1.0
CPE cpe:2.3:a:mozilla:thunderbird:::::::: Remediation No remediation found in references.

Change History

6 change records found show changes

Date	Action	Recorded By
Sep 1, 2026	CVE Modified	[email protected]
Aug 24, 2026	CVE Modified	[email protected]
Aug 19, 2026	Initial Analysis	[email protected]
Aug 19, 2026	CVE Modified	CISA-ADP
Aug 18, 2026	CVE Modified	[email protected]
Aug 18, 2026	New CVE Received	[email protected]