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 the buffer for the headers, and potentially crashing Thunderbird. This vulnerability was fixed in Thunderbird 153 and Thunderbird 140.13.

CVSS v3 7.5 HIGH

7.5^/10

CVSS v3 : HIGH

Vector :

Exploitability : 3.9 / Impact : 3.6

Attack Vector NETWORK

Attack Complexity LOW

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact NONE

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://bugzilla.mozilla.org/show_bug.cgi?id=2046137	Permissions Required
https://www.mozilla.org/security/advisories/mfsa2026-71/	Vendor Advisory
https://www.mozilla.org/security/advisories/mfsa2026-72/	Vendor Advisory

Configurations

Configuration 1 (hide)

cpe:2.3:a:mozilla:thunderbird:*:*:*:*:esr:*:*:*

History

No history.

Information

Published : 2026-07-22 20:16

Updated : 2026-08-12 00:25

NVD link : CVE-2026-14899

Mitre link : CVE-2026-14899

CVE.ORG link : CVE-2026-14899

JSON object : View

Products Affected

mozilla

thunderbird

CWE

CWE-193

Off-by-one Error

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