PT-2026-3902

Name of the Vulnerable Software and Affected Versions Mastodon versions prior to 4.5.5 Mastodon versions prior to 4.4.12 Mastodon versions prior to 4.3.18 Description Mastodon is a social network server. An insecure direct object reference exists in the web push subscription update endpoint. An...

PT-2026-3901

Name of the Vulnerable Software and Affected Versions Mastodon versions prior to 4.5.5 Mastodon versions prior to 4.4.12 Mastodon versions prior to 4.3.18 Description Mastodon, a free and open-source social network server based on ActivityPub, does not limit the length of names for lists or...

Mastodon security vulnerabilities

Mastodon is an open-source social networking server based on ActivityPub. Versions of Mastodon prior to 4.3.18, 4.4.12, and 4.5.5 contained security vulnerabilities. These vulnerabilities stemmed from the lack of restrictions on the maximum number of remote post voting options, which could lead t...

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...

BIT-MASTODON-2026-22245 Mastodon has SSRF Protection bypass

Mastodon is a free, open-source social network server based on ActivityPub. By nature, Mastodon performs a lot of outbound requests to user-provided domains. Mastodon, however, has some protection mechanism to disallow requests to local IP addresses unless specified in ALLOWEDPRIVATEADDRESSES to...

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-2026-22245

Mastodon is a free, open-source social network server based on ActivityPub. By nature, Mastodon performs a lot of outbound requests to user-provided domains. Mastodon, however, has some protection mechanism to disallow requests to local IP addresses unless specified in ALLOWEDPRIVATEADDRESSES to...

CVE-2022-31263

app/models/user.rb in Mastodon before 3.5.0 allows a bypass of e-mail restrictions...

CVE-2024-34535

In Mastodon 4.1.6, API endpoint rate limiting can be bypassed by setting a crafted HTTP request header...

CVE-2026-22245

Mastodon is a free, open-source social network server based on ActivityPub. By nature, Mastodon performs a lot of outbound requests to user-provided domains. Mastodon, however, has some protection mechanism to disallow requests to local IP addresses unless specified in ALLOWEDPRIVATEADDRESSES to...

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 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...

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...

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-2026-22245 Mastodon has SSRF Protection bypass

Mastodon is a free, open-source social network server based on ActivityPub. By nature, Mastodon performs a lot of outbound requests to user-provided domains. Mastodon, however, has some protection mechanism to disallow requests to local IP addresses unless specified in ALLOWEDPRIVATEADDRESSES to...

CVE-2026-22245 Mastodon has SSRF Protection bypass

Mastodon is a free, open-source social network server based on ActivityPub. By nature, Mastodon performs a lot of outbound requests to user-provided domains. Mastodon, however, has some protection mechanism to disallow requests to local IP addresses unless specified in ALLOWEDPRIVATEADDRESSES to...

EUVD-2026-1674

Mastodon is a free, open-source social network server based on ActivityPub. By nature, Mastodon performs a lot of outbound requests to user-provided domains. Mastodon, however, has some protection mechanism to disallow requests to local IP addresses unless specified in ALLOWEDPRIVATEADDRESSES to...

CVE-2026-22245

CVE-2026-22245 — Mastodon SSRF protection bypass . The issue affects Mastodon releases prior to 4.5.4, 4.4.11, 4.3.17 and 4.2.29, where the local/loopback access protection for outbound HTTP requests relied on a incomplete disallowed IP ranges list. An attacker could use certain IPs to trigger re...