CVE-2026-84142

CRITICAL 9.8CVE-2026-84142 · Published 01/09/2026 · updated 03/09/2026

Package	Affected versions	Patched versions
firefox mozilla	`< 155.0.0`	`155.0.0`
thunderbird mozilla	`< 155.0`	`155.0`

Description

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.

References

bugzilla.mozilla.org/buglist.cgi · Issue Tracking
bugzilla.mozilla.org/buglist.cgi · Issue Tracking
mozilla.org/security/advisories/mfsa2026-82 · Vendor Advisory
mozilla.org/security/advisories/mfsa2026-86 · Vendor Advisory

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