CVE-2026-84143
Internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15
- State
- Published
- Severity
- 9.8 Critical
- Published
- Sep 1, 2026
- Updated
- Sep 3, 2026
- Reserved
- Sep 1, 2026
Description
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 9.8 Critical | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H | CISA-ADP |
Weaknesses
- CWE-200 Exposure of Sensitive Information to an Unauthorized Actor
Affected Products
| Product | Versions |
|---|---|
FirefoxMozilla |
|
ThunderbirdMozilla |
|
References
- High Severity internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15
- Moderate Severity internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15
- Low Severity internally found bugs fixed in Thunderbird 155, Thunderbird ESR 153.2 and Thunderbird ESR 140.15
- https://www.mozilla.org/security/advisories/mfsa2026-82/
- https://www.mozilla.org/security/advisories/mfsa2026-84/
- https://www.mozilla.org/security/advisories/mfsa2026-85/
- https://www.mozilla.org/security/advisories/mfsa2026-86/
- https://www.mozilla.org/security/advisories/mfsa2026-87/
- https://www.mozilla.org/security/advisories/mfsa2026-88/
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