7.5
High
CVE-2026-14899 The code to parse MIME headers for display when forwarding a message (if the setting to view all headers was enabled)…
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.
Affected products and versions
| Product | Affected versions | Fixed in |
|---|---|---|
| Thunderbird 153 | earliest → < 153 | 153 |
| Thunderbird 140.13 | earliest → < 140.13 | 140.13 |
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