CVE-2026-50129

CVE-2026-50129 affects Mastodon before versions 4.5.11, 4.4.18, and 4.3.24. The issue is a DoS caused by an uncaught exception in the math sanitizer’s MATH_TRANSFORMER due to missing exception handling; malformed nodes can crash the server or disrupt services depending on the action and interact...

CVE-2026-50129 Mastodon: Persistent anonymous DoS via unhandled NoMethodError in MATH_TRANSFORMER

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.11, 4.4.18, and 4.3.24, a DoS can be triggered by Uncaught Exception vulerability, due to missing exception handling in the math sanitizer. Malformed nodes can result in a DoS of a whole server or targeted...

CVE-2026-50129

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.11, 4.4.18, and 4.3.24, a DoS can be triggered by Uncaught Exception vulerability, due to missing exception handling in the math sanitizer. Malformed nodes can result in a DoS of a whole server or targeted...

CVE-2026-50128 Mastodon: Spoofing of attribution domains

Mastodon is a free, open-source social network server based on ActivityPub. From 4.3.0 until 4.5.11 and 4.4.18, Mastodon has a feature to let websites credit authors of their articles. To prevent false attribution claims, Mastodon uses the attributionDomains JSON-LD term, however, an error in how...

CVE-2026-50128

Mastodon vulnerability CVE-2026-50128 affects versions 4.3.0 through 4.5.11 and 4.4.18, where an error in the attributionDomains JSON-LD handling allows an attacker to arbitrarily modify the attributionDomains value on a legitimately signed Update and bypass signature verification. This can under...

CVE-2026-50128 Mastodon: Spoofing of attribution domains

Mastodon is a free, open-source social network server based on ActivityPub. From 4.3.0 until 4.5.11 and 4.4.18, Mastodon has a feature to let websites credit authors of their articles. To prevent false attribution claims, Mastodon uses the attributionDomains JSON-LD term, however, an error in how...

CVE-2026-50128

Mastodon is a free, open-source social network server based on ActivityPub. From 4.3.0 until 4.5.11 and 4.4.18, Mastodon has a feature to let websites credit authors of their articles. To prevent false attribution claims, Mastodon uses the attributionDomains JSON-LD term, however, an error in how...

CVE-2026-48028

Mastodon (open-source social network server) versions prior to 4.5.10, 4.4.17, and 4.3.23 are affected. The vulnerability arises from how incoming activities signed with Linked-Data Signatures are normalized, failing to adequately protect against a class of spoofing that lets an attacker remove J...

CVE-2026-48028 Mastodon: Removal of integrity-protected JSON entries from signed activities

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, Mastodon's normalization of incoming activities signed with Linked-Data Signatures does not sufficiently protect the activities from a certain class of spoofing, allowing threat actors...

CVE-2026-48028 Mastodon: Removal of integrity-protected JSON entries from signed activities

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, Mastodon's normalization of incoming activities signed with Linked-Data Signatures does not sufficiently protect the activities from a certain class of spoofing, allowing threat actors...

CVE-2026-48028

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, Mastodon's normalization of incoming activities signed with Linked-Data Signatures does not sufficiently protect the activities from a certain class of spoofing, allowing threat actors...

CVE-2026-47389

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, when using Ruby versions older than 3.4, PrivateAddressCheck.privateaddress? returns false for IPv4-mapped IPv6 addresses ::ffff:a.b.c.d corresponding to some private IPv4 addresses,...

CVE-2026-47389 Mastodon: SSRF protection bypass on older Ruby versions

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, when using Ruby versions older than 3.4, PrivateAddressCheck.privateaddress? returns false for IPv4-mapped IPv6 addresses ::ffff:a.b.c.d corresponding to some private IPv4 addresses,...

CVE-2026-47389

Mastodon vulnerability CVE-2026-47389 affects older Ruby runtimes (

CVE-2026-47389 Mastodon: SSRF protection bypass on older Ruby versions

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, when using Ruby versions older than 3.4, PrivateAddressCheck.privateaddress? returns false for IPv4-mapped IPv6 addresses ::ffff:a.b.c.d corresponding to some private IPv4 addresses,...

CVE-2026-46349

CVE-2026-46349 affects Mastodon before versions 4.5.10, 4.4.17, and 4.3.23. The issue arises from Mastodon’s normalization of incoming activities signed with Linked-Data Signatures, which does not sufficiently prevent a class of spoofing. An attacker could re-arrange a valid signed JSON-LD activi...

CVE-2026-46349

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, Mastodon's normalization of incoming activities signed with Linked-Data Signatures does not sufficiently protect the activities from a certain class of spoofing, allowing attackers to...

CVE-2026-46349 Mastodon: LD-Signature Bypass via JSON-LD Named-Graph Restructuring

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, Mastodon's normalization of incoming activities signed with Linked-Data Signatures does not sufficiently protect the activities from a certain class of spoofing, allowing attackers to...

CVE-2026-46349 Mastodon: LD-Signature Bypass via JSON-LD Named-Graph Restructuring

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, Mastodon's normalization of incoming activities signed with Linked-Data Signatures does not sufficiently protect the activities from a certain class of spoofing, allowing attackers to...

CVE-2026-46348 Mastodon: SSRF Bypass via IPv6 Unspecified Address (::)

Mastodon is a free, open-source social network server based on ActivityPub. Prior to 4.5.10, 4.4.17, and 4.3.23, the list of disallowed IP address ranges was lacking an IP address range that can be used to reach local IP addresses. An attacker can use an IP address in the affected range to make...