← back
CVE-2026-14899highCWE-193

Off-by-one out of bounds read in MIME header parser for forwarding

21Vexday Risk Score

No sign of exploitation. No public exploitation artifact known so far.

ssvc Trackcvss 7.5epss 0.3%
exploitation probability
0.3%top 82% of all CVEs
observed exploitation
nono source reports it
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 · Thunderbird