CVE-2026-84143

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.

CVSS v3 9.8 CRITICAL

9.8^/10

CVSS v3 : CRITICAL

Vector :

Exploitability : 3.9 / Impact : 5.9

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2048793%2C2054645%2C2057114%2C2059109%2C2061287	Issue Tracking
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054631%2C2054657%2C2055007%2C2055681%2C2057107%2C2058087%2C2058088%2C2058090%2C2058095%2C2058101%2C2059183%2C2059185%2C2061301%2C2061325	Issue Tracking
https://bugzilla.mozilla.org/show_bug.cgi?id=2057108	Issue Tracking
https://www.mozilla.org/security/advisories/mfsa2026-82/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-84/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-85/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-86/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-87/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-88/	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	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::::::::

History

No history.

Information

Published : 2026-09-01 13:20

Updated : 2026-09-03 18:17

NVD link : CVE-2026-84143

Mitre link : CVE-2026-84143

CVE.ORG link : CVE-2026-84143

JSON object : View

Products Affected

mozilla

thunderbird
firefox

CWE

CWE-119

Improper Restriction of Operations within the Bounds of a Memory Buffer

CWE-200

Exposure of Sensitive Information to an Unauthorized Actor

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