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Medium 6.3Published Sep 30, 2026
CVE-2026-103500Heap buffer overflow opening large email
Updated under an hour ago ()
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It affects Mozilla Thunderbird. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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An attacker could cause a heap buffer overflow by getting a user to open an email that is greater than or equal to 2GB in size. This vulnerability was fixed in Thunderbird 157, Thunderbird 140.17, and Thunderbird 153.4.
- CVSS
- 6.3 MEDIUM (v3.1, CISA ADP)CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:L
- Weakness (CWE)
- CWE-122
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- mozilla
- NVD analysis
- Modified
- Record last updated
- Oct 16, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Mozilla Thunderbird mozilla:thunderbird (from the name) | 140.17 builds before 140.* not affected; 153.4 builds before 153.* not affected; from 157 not affected | CNA record |
mozilla thunderbird mozilla:thunderbird | before 140.17.0; from 141.0 before 153.4.0; from 154.0 before 157.0 | NVD |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2070267permissions-required
- https://www.mozilla.org/security/advisories/mfsa2026-101/vendor-advisory
- https://www.mozilla.org/security/advisories/mfsa2026-102/vendor-advisory
- https://www.mozilla.org/security/advisories/mfsa2026-103/vendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.