#VU111055 Input validation error in Mozilla Thunderbird - CVE-2025-5986
Published: June 11, 2025
Vulnerability identifier: #VU111055
Vulnerability risk: Medium
CVSSv4.0: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N/E:U/U:Green
CVE-ID: CVE-2025-5986
CWE-ID: CWE-20
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerable software:
Mozilla Thunderbird
Mozilla Thunderbird
Software vendor:
Mozilla
Mozilla
Description
The vulnerability allows a remote attacker to gain access to sensitive information or perform a denial of service (DoS) attack.
The vulnerability exists due to insufficient validation of user-supplied input when handling mailbox:/// links. A remote attacker can create a specially crafted email mailbox:/// links and trigger unsolicited downloads of .pdf files to the user's desktop or home directory without prompting, even if auto-saving is disabled. Additionally, this behavior can be use to leak Windows credentials via SMB links when the email is viewed in HTML mode.
Note, viewing the email in HTML mode is enough to load external content.
Remediation
Install updates from vendor's website.