Input validation error in Mozilla Thunderbird - CVE-2025-3909
Published: May 14, 2025
Vulnerability identifier: #VU109192
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2025-3909
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Mozilla
Affected software:
Mozilla Thunderbird
Mozilla Thunderbird
Detailed vulnerability description
The vulnerability allows a remote attacker to execute arbitrary JavaScript code.
The vulnerability exists due to incorrect handling of the X-Mozilla-External-Attachment-URL header. A remote attacker can create a nested email attachment, set its content type to application/pdf and force the application to execute arbitrary JavaScript code in the file:/// context.
How to mitigate CVE-2025-3909
Install updates from vendor's website.