One byte overflow read in mail parser
Summary
| CVE | CVE-2026-84640 |
|---|---|
| State | PUBLISHED |
| Assigner | mozilla |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-09-01 22:17:19 UTC |
| Updated | 2026-09-01 22:17:19 UTC |
| Description | A maliciously constructed mail header could lead to a one byte read past the end of a buffer. This vulnerability was fixed in Thunderbird 155, Thunderbird 140.15, and Thunderbird 153.2. |
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Mozilla | Thunderbird | unaffected 140.15 140.* rpm | Not specified |
| CNA | Mozilla | Thunderbird | unaffected 153.2 153.* rpm | Not specified |
| CNA | Mozilla | Thunderbird | unaffected 155 * rpm | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| bugzilla.mozilla.org/show_bug.cgi | [email protected] | bugzilla.mozilla.org | |
| www.mozilla.org/security/advisories/mfsa2026-88 | [email protected] | www.mozilla.org | |
| www.mozilla.org/security/advisories/mfsa2026-87 | [email protected] | www.mozilla.org | |
| www.mozilla.org/security/advisories/mfsa2026-86 | [email protected] | www.mozilla.org | |
| CVE Program record | CVE.ORG | www.cve.org | canonical |
| NVD vulnerability detail | NVD | nvd.nist.gov | canonical, analysis |
Vendor Comments And Credit
Discovery Credit
CNA: Ramesh Adhikari, Dr. Faruk Kazi (CoE-CNDS Lab, VJTI, Mumbai, India) (en)
There are currently no legacy QID mappings associated with this CVE.