Vulnerability Description
Thunderbird's check that prevents mailbox: URLs from accessing files on remote Windows network shares could be bypassed using extended-length UNC paths. Displaying a specially crafted email could cause Thunderbird to connect to an SMB server chosen by the attacker, disclosing the user's Windows account name and NTLM authentication data, which could be used for offline password cracking or relay attacks. This bug only affects Thunderbird on Windows. Other operating systems are unaffected. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.
References
- https://bugzilla.mozilla.org/show_bug.cgi?id=2081141
- https://www.mozilla.org/security/advisories/mfsa2026-121/
- https://www.mozilla.org/security/advisories/mfsa2026-122/
FAQ
What is CVE-2026-118176?
CVE-2026-118176 is a documented vulnerability. Thunderbird's check that prevents mailbox: URLs from accessing files on remote Windows network shares could be bypassed using extended-length UNC paths. Displaying a specially crafted email could caus...
How severe is CVE-2026-118176?
CVSS scoring is not yet available for CVE-2026-118176. Check NVD for updates.
Is there a patch for CVE-2026-118176?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.