EUVD-2026-62844

Lemmy is a link aggregator and forum for the fediverse. Prior to 0.19.19 and 1.0.0-alpha.18, a lower-ranked remote moderator can remove a higher-ranked moderator by sending a signed ActivityPub Remove activity to the target instance. The local API uses LocalUser::ishighermodoradmincheck to enforc...

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-2026-42462

Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Prior to versions 1.9.11, 1.10.10, 2.0.18, 2.1.14, and 2.2.3, an attacker can make use of JSON-LD features to restructure a JSON-LD document that would change how Fedify interprets it without changing its...

CVE-2026-42462

CVE-2026-42462 describes an LD-Signature bypass in Fedify caused by JSON-LD named-graph restructuring. The issue allows an attacker to reorganize a signed JSON-LD payload (via features like @graph, @reverse, @included) in a way that changes how the signed ActivityPub activity is interpreted witho...

EUVD-2026-36127

Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Prior to versions 1.9.11, 1.10.10, 2.0.18, 2.1.14, and 2.2.3, an attacker can make use of JSON-LD features to restructure a JSON-LD document that would change how Fedify interprets it without changing its...

CVE-2026-42462 Fedify has an LD-Signature Bypass via JSON-LD Named-Graph Restructuring

Fedify is a TypeScript library for building federated server apps powered by ActivityPub. Prior to versions 1.9.11, 1.10.10, 2.0.18, 2.1.14, and 2.2.3, an attacker can make use of JSON-LD features to restructure a JSON-LD document that would change how Fedify interprets it without changing its...