CVE-2026-84144
highInternally found bugs present in Thunderbird 154 and Thunderbird ESR 153.1.
Vendor / product: Mozilla — firefox
Internally found bugs present in Thunderbird 154 and Thunderbird ESR 153.1. 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 153.2, Thunderbird 155, and Thunderbird 153.2.
CVSS
7.5
7.5 (CVSS v3.1)
CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H Severity source: NVD CVSS v3.1 (134c704f-9b21-4f2e-91b3-4a467353bcc0)
Timeline (UTC)
Published: 2026-09-01 13:20
Modified: 2026-09-03 16:33
NVD status: Analyzed
Last synced 2 days ago
Verified against the source API 2026-10-27 06:50 UTC
Exploitation
Not listed in CISA KEV (as of last catalog sync)
Absence from KEV does not mean a CVE is not exploited. Exploitation status: unknown (no authoritative evidence in our sources).
Affected products
mozilla / firefox <153.2.0, ≥154.0.0 <155.0.0
mozilla / thunderbird <153.2.0, ≥154.0 <155.0
Weakness classification (CWE)
Source: NVD / CISA. “NVD-CWE-Other” and “NVD-CWE-noinfo” mean NVD could not assign a specific weakness.
Mitigation & advisories
Vendor advisory: https://www.mozilla.org/security/advisories/mfsa2026-82/
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/mfsa2026-88/
References
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054619%2C2054620%2C2054624%2C2054702%2C20... security@mozilla.org
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054625%2C2059002%2C2061775 security@mozilla.org
- https://bugzilla.mozilla.org/buglist.cgi?bug_id=2054691%2C2058085%2C2059144%2C2059191%2C20... security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-82/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-85/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-86/ security@mozilla.org
- https://www.mozilla.org/security/advisories/mfsa2026-88/ security@mozilla.org
Data sources
NVD CVE API 2.0 — fetched 2026-10-27 06:50 UTC · record ↗