CVE-2026-14899 — Off-by-one out of bounds read in MIME header parser for forwarding
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 …
Published: 2026-07-22 · CVSS: 7.5 · CVSS 3.1
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.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7