CVE-2026-14899
Last modified
CVE-2026-14899 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. The code to parse MIME headers for display when forwarding a message (if the setting to view all headers was enabled) had an off-by-one error, allowing a single byte to be read from the memory after the buffer for the headers, and potentially crashing Thunderbird. This vulnerability was fixed in Thunderbird 153 and Thunderbird 140.13.. EPSS estimates a 0.26% chance of exploitation in the next 30 days.
Description
The code to parse MIME headers for display when forwarding a message (if the setting to view all headers was enabled) had an off-by-one error, allowing a single byte to be read from the memory after the buffer for the headers, and potentially crashing Thunderbird. This vulnerability was fixed in Thunderbird 153 and Thunderbird 140.13.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Mozilla | Thunderbird | < 140.13.0 |
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2046137Permissions Required
- https://www.mozilla.org/security/advisories/mfsa2026-71/Vendor Advisory
- https://www.mozilla.org/security/advisories/mfsa2026-72/Vendor Advisory
Timeline
- Published
- Last Modified
- Status
- Analyzed
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