CVE-2026-84142

Internally found bugs present in Thunderbird 154. 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 and Thunderbird 155.

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=2029421%2C2040889%2C2045313%2C2045435%2C2053578%2C2058621%2C2058626	Issue Tracking
https://bugzilla.mozilla.org/buglist.cgi?bug_id=2048796%2C2053150%2C2057356	Issue Tracking
https://www.mozilla.org/security/advisories/mfsa2026-82/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-86/	Vendor Advisory

Configurations

Configuration 1 (hide)

OR	cpe:2.3:a:mozilla:firefox::::::::
	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-2026-84142

Mitre link : CVE-2026-84142

CVE.ORG link : CVE-2026-84142

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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