Not yet scoredPublished Oct 27, 2026

CVE-2026-118176Bypass of remote UNC path restriction in mailbox: URLs

Updated under an hour ago (Oct 28, 2026, 12:00 PM ET)

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It affects Mozilla Thunderbird. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Every CVE for Mozilla Thunderbird

Exploited in the last 30 days

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.

CVSS: Not yet scored
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: mozilla
NVD analysis: Deferred
Record last updated: Oct 27, 2026
First seen by InfoSec Signals: Oct 27, 2026

Affected products

Affected products

Mozilla Thunderbird mozilla:thunderbird (from the name)	153.6 builds before 153.* not affected; from 159 not affected	CNA record

References

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/

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.