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HIGH · 7.5

CVE-2026-14899

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 t...

Vulnerability 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.

CVSS Score

7.5

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N
Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
NONE
Availability
NONE

Affected Products

VendorProductVersions
MozillaThunderbird< 140.13.0

Related Weaknesses (CWE)

CWE-193

References

FAQ

What is CVE-2026-14899?

CVE-2026-14899 is a vulnerability with a CVSS score of 7.5 (HIGH). 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 t...

How severe is CVE-2026-14899?

CVE-2026-14899 has been rated HIGH with a CVSS base score of 7.5/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2026-14899?

Check the references section above for vendor advisories and patch information. Affected products include: Mozilla Thunderbird.