CVE-2026-118180

thunderbird: When logging in to a Matrix account, Thunderbird used the homeserver address provided in the server's login response...

CVE-2026-118180 is fixed in thunderbird on 1 platform, first by DEBIAN-CVE-2026-118180, released October 31, 2026. It is not reported as exploited. Patch Radar priority: High.

High
CVSS
7.5
high
Exploitation
None reported
No vendor assessment
CISA KEV
Not listed
Not in the Known Exploited Vulnerabilities catalog
EPSS
0.0032
25th percentile

When logging in to a Matrix account, Thunderbird used the homeserver address provided in the server's login response without validating it. A malicious or compromised homeserver could provide a file: URL, causing Thunderbird to send all further Matrix requests of that session to local files or, on Windows, to an attacker-controlled network share, which could leak the user's NTLM credentials. The NTLM credential leak only affects Thunderbird on Windows. Other operating systems are unaffected. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.

Where it's fixed

ProductFixed inFixReleased
Linux
thunderbird · Debian 12.15 (bookworm) 1:153.6.0esr-1~deb12u2 DEBIAN-CVE-2026-118180 Oct 31, 2026
thunderbird · Debian 13.5 (trixie) 1:153.6.0esr-1~deb13u1 DEBIAN-CVE-2026-118180 Oct 31, 2026

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