CVE-2026-118176
Thunderbird's check that prevents mailbox: URLs from accessing files on remote Windows network…
- Risk score
- 56/100
- CVSS
- 8.1 v3.1
- Exploit chance (30 days)
- 0.2%
- Published
- 27 Oct 2026
Open in the live forecast Today's forecast
What to know
- What it is
- 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 a…
- Affected
- See advisory
- Fix
- Apply the vendor's security update; see the linked advisory.
- Exploitation
- No known exploitation
Why it is Yellow
- CVSS 8.1 high
- Remotely exploitable without logging in
References
Original 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.
Last activity 27 Oct 2026. Patch Forecast updates every hour.