BIT-MASTODON-2026-22246 Local Mastodon users can enumerate and access severed relationships of every other local user

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon 4.3 added notifications of severed relationships, allowing end-users to inspect the relationships they lost as the result of a moderation action. The code allowing users to download lists of severed relationships...

CVE-2026-22246

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon 4.3 added notifications of severed relationships, allowing end-users to inspect the relationships they lost as the result of a moderation action. The code allowing users to download lists of severed relationships...

CVE-2026-22246

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon 4.3 added notifications of severed relationships, allowing end-users to inspect the relationships they lost as the result of a moderation action. The code allowing users to download lists of severed relationships...

CVE-2026-22246

Mastodon vulnerability (CVE-2026-22246): In 4.3, the severed-relationships notification feature allowed inspecting lost relationships, but the code that downloads lists of severed relationships did not verify the list owner. As a result, any registered local user could enumerate and access the se...

CVE-2026-22246 Local Mastodon users can enumerate and access severed relationships of every other local user

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon 4.3 added notifications of severed relationships, allowing end-users to inspect the relationships they lost as the result of a moderation action. The code allowing users to download lists of severed relationships...

CVE-2026-22246 Local Mastodon users can enumerate and access severed relationships of every other local user

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon 4.3 added notifications of severed relationships, allowing end-users to inspect the relationships they lost as the result of a moderation action. The code allowing users to download lists of severed relationships...

EUVD-2026-1675

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon 4.3 added notifications of severed relationships, allowing end-users to inspect the relationships they lost as the result of a moderation action. The code allowing users to download lists of severed relationships...