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CVE PROGRAM SOURCE RECORD7.5 High

CVE-2026-14899

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

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

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Mozilla Thunderbird

  • 140.13 to ≤ 140.*unaffected
  • 153 to ≤ *unaffected

References