CVE-2026-118178 is a vulnerability in Mozilla Thunderbird
Published on October 27, 2026
RSS feed could redirect its subscription to a local file or network share
A remote RSS feed could use the itunes:new-feed-url or newLocation element to permanently change its stored subscription URL to a file: URL. Thunderbird then read that location on every feed update. This allowed a malicious feed, or an attacker able to modify a feed delivered over HTTP, to make Thunderbird read local files and, on Windows, connect 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 affected by the local file read only. This vulnerability was fixed in Thunderbird 159 and Thunderbird 153.6.
Vulnerability Analysis
CVE-2026-118178 is exploitable with network access, requires user interaction and a small amount of user privileges. This vulnerability is considered to have a low attack complexity. The potential impact of an exploit of this vulnerability is considered to have a high impact on confidentiality, with no impact on integrity and availability.
Weakness Type
Inclusion of Functionality from Untrusted Control Sphere
The software imports, requires, or includes executable functionality (such as a library) from a source that is outside of the intended control sphere.
Products Associated with CVE-2026-118178
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Affected Versions
Mozilla Thunderbird:- Version 153.6, <= 153.* is unaffected.
- Version 159, <= * is unaffected.