CVE-2026-14899: high-severity vulnerability in Mozilla Thunderbird
Off-by-one out of bounds read in MIME header parser for forwarding
Published · Updated
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21Vexday Risk Score
No sign of exploitation. No public exploitation artifact known so far.
ssvc Trackcvss 7.5epss 0.5%
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.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Affected products
Mozilla · ThunderbirdRelated CVEs — Mozilla Thunderbird
In the same product, most dangerous first.