CVE-2026-23961

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon allows server administrators to suspend remote users to prevent interactions. However, some logic errors allow already-known posts from such suspended users to appear in timelines if boosted. Furthermore, under...

EUVD-2026-4210

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.5, 4.4.12, and 4.3.18, an insecure direct object reference in the web push subscription update endpoint lets any authenticated user update another user's push subscription by guessing or obtaining th...

CVE-2026-23964 Mastodon has insufficient access control to push notification settings

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.5, 4.4.12, and 4.3.18, an insecure direct object reference in the web push subscription update endpoint lets any authenticated user update another user's push subscription by guessing or obtaining th...

CVE-2026-23964 Mastodon has insufficient access control to push notification settings

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.5, 4.4.12, and 4.3.18, an insecure direct object reference in the web push subscription update endpoint lets any authenticated user update another user's push subscription by guessing or obtaining th...

CVE-2026-23964

Mastodon vendor: Mastodon server (ActivityPub). Vulnerability CVE-2026-23964 is an insecure direct object reference in the web push subscription update endpoint affecting versions < 4.5.5, < 4.4.12, and

CVE-2026-23964 Mastodon has insufficient access control to push notification settings

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.5, 4.4.12, and 4.3.18, an insecure direct object reference in the web push subscription update endpoint lets any authenticated user update another user's push subscription by guessing or obtaining th...

EUVD-2026-4209

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.5, 4.4.12, and 4.3.18, the server does not enforce a maximum length for the names of lists or filters, or for filter keywords, allowing any user to set an arbitrarily long string as the name or...

CVE-2026-23963 Mastodon missing length limits on list names, filter names, and filter keywords

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.5, 4.4.12, and 4.3.18, the server does not enforce a maximum length for the names of lists or filters, or for filter keywords, allowing any user to set an arbitrarily long string as the name or...

CVE-2026-23963

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.5, 4.4.12, and 4.3.18, the server does not enforce a maximum length for the names of lists or filters, or for filter keywords, allowing any user to set an arbitrarily long string as the name or...

CVE-2026-23963 Mastodon missing length limits on list names, filter names, and filter keywords

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.5, 4.4.12, and 4.3.18, the server does not enforce a maximum length for the names of lists or filters, or for filter keywords, allowing any user to set an arbitrarily long string as the name or...

CVE-2026-23963

CVE-2026-23963 affects Mastodon prior to versions 4.5.5, 4.4.12, and 4.3.18 where there is no maximum length enforcement for list names, filter names, or filter keywords. This can enable a local user to craft arbitrarily long strings, leading to disproportionate storage and compute resource usage...

CVE-2026-23963 Mastodon missing length limits on list names, filter names, and filter keywords

Mastodon is a free, open-source social network server based on ActivityPub. Prior to versions 4.5.5, 4.4.12, and 4.3.18, the server does not enforce a maximum length for the names of lists or filters, or for filter keywords, allowing any user to set an arbitrarily long string as the name or...

CVE-2026-23962

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon versions before v4.3.18, v4.4.12, and v4.5.5 do not have a limit on the maximum number of poll options for remote posts, allowing attackers to create polls with a very large amount of options, greatly increasing...

EUVD-2026-4208

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon versions before v4.3.18, v4.4.12, and v4.5.5 do not have a limit on the maximum number of poll options for remote posts, allowing attackers to create polls with a very large amount of options, greatly increasing...

CVE-2026-23962 Mastodon vulnerable to Denial of Service from a single post (client/server)

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon versions before v4.3.18, v4.4.12, and v4.5.5 do not have a limit on the maximum number of poll options for remote posts, allowing attackers to create polls with a very large amount of options, greatly increasing...

CVE-2026-23962

Mastodon is vulnerable to Denial of Service due to an unlimited maximum number of poll options for remote posts in versions before v4.3.18, v4.4.12, and v4.5.5. The underlying issue allows an attacker to create polls with a very large number of options, leading to disproportionate resource usage ...

CVE-2026-23962 Mastodon vulnerable to Denial of Service from a single post (client/server)

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon versions before v4.3.18, v4.4.12, and v4.5.5 do not have a limit on the maximum number of poll options for remote posts, allowing attackers to create polls with a very large amount of options, greatly increasing...

CVE-2026-23962 Mastodon vulnerable to Denial of Service from a single post (client/server)

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon versions before v4.3.18, v4.4.12, and v4.5.5 do not have a limit on the maximum number of poll options for remote posts, allowing attackers to create polls with a very large amount of options, greatly increasing...

CVE-2026-23961

Mastodon is a free, open-source social network server based on ActivityPub. Mastodon allows server administrators to suspend remote users to prevent interactions. However, some logic errors allow already-known posts from such suspended users to appear in timelines if boosted. Furthermore, under...

CVE-2026-23961

Summary of CVE-2026-23961 (Mastodon): A logic flaw in how suspended remote users are handled allows old posts from those users to appear in timelines, and under some circumstances, newly created posts from suspended users can be processed and surfaced. Affected releases span multiple lines: v4.5....