CVE-2026-14899

Published: Jul 22, 2026Modified: Aug 12, 2026

7.5

Vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

Exploitability: 3.9 / Impact: 3.6

Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary)

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 (1)

Products: Mozilla: Thunderbird

1 product

Configuration A

1 vulnerable

Vulnerable Software	Affected Versions
Mozilla Thunderbird	Before 140.13.0

Related CWEs

Off-by-one Error

A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value.

References (3)

https://bugzilla.mozilla.org/show_bug.cgi?id=2046137

Source: security@mozilla.org

Permissions Required

https://www.mozilla.org/security/advisories/mfsa2026-71/

Source: security@mozilla.org

Vendor Advisory

https://www.mozilla.org/security/advisories/mfsa2026-72/

Source: security@mozilla.org

Vendor Advisory

Timeline

No history available yet.