CVE-2026-14899
Off-by-one out of bounds read in MIME header parser for forwarding
- State
- Published
- Severity
- 7.5 High
- Published
- Jul 22, 2026
- Updated
- Jul 27, 2026
- Reserved
- Jul 6, 2026
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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 3.1 | 7.5 High | CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N | CISA-ADP |
Weaknesses
- CWE-193 Off-by-one Error
Affected Products
| Product | Versions |
|---|---|
ThunderbirdMozilla |
|
References
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