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.
Affected products
mozilla: firefox; mozilla: thunderbird
References4
- www.mozilla.org/security/advisories/mfsa2026-82/ Vendor Advisory
- www.mozilla.org/security/advisories/mfsa2026-86/ Vendor Advisory
- bugzilla.mozilla.org/buglist.cgi?bug_id=2029421%2C2040889%2C204… Issue Tracking
- bugzilla.mozilla.org/buglist.cgi?bug_id=2048796%2C2053150%2C205… Issue Tracking
Metrics
- CVSS 3.1
-
9.8
CRITICAL
Score source: NVD
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 1% percentile: 47 · as of 8 November 2026
- CWE
- CWE-119CWE-200
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