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CVE-2026-84144Internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2
- 7.5HighCVSS base score
- 0.43%Exploitation in 30 daysEPSS · top 63% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
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.
Timeline
ID reserved
By mozilla
Published
- 2 days later
· 2 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
| Scored by | CVSS | Score | Vector |
|---|---|---|---|
| CISA-ADPADP (enrichment) | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H |
| NVDNVD · Analyzed | 3.1 | High7.5 | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:H |
- EPSS (exploitation in 30 days)
- 0.43% · top 63% of all CVEs (13 Nov 2026)
- CISA SSVC
- Exploitation: none · Automatable: no · Technical impact: total
Loading the EPSS history…
The list uses the assigner's score when there is one, then CISA's, then NVD's: High 7.5.
Affected products
- unaffected 153.2 – ≤ 153.*
- unaffected 155 – ≤ *
- unaffected 153.2 – ≤ 153.*
- unaffected 155 – ≤ *
References
References7
- Moderate Severity internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2 (opens in a new tab)
- High Severity internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2 (opens in a new tab)
- Low Severity internally found bugs fixed in Thunderbird 155 and Thunderbird ESR 153.2 (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2026-82/ (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2026-85/ (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2026-86/ (opens in a new tab)
- https://www.mozilla.org/security/advisories/mfsa2026-88/ (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-69092 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-84144)Record last updated .