Bug 2562313 (CVE-2026-118176) - CVE-2026-118176 thunderbird: Bypass of remote UNC path restriction in mailbox: URLs
Summary: CVE-2026-118176 thunderbird: Bypass of remote UNC path restriction in mailbox...
Keywords:
Status: NEW
Alias: CVE-2026-118176
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
high
high
Target Milestone: ---
Assignee: Product Security
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-10-27 18:31 UTC by OSIDB Bzimport
Modified: 2026-10-29 14:45 UTC (History)
5 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
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Description OSIDB Bzimport 2026-10-27 18:31:49 UTC 
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.
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