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 Link…
Published: 2026-06-24 · CVSS: 5.3 · CVSS 3.1
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 re-arrange a valid signed JSON-LD activity from a third-party actor to have it processed differently. This vulnerability is fixed in 4.5.10, 4.4.17, and 4.3.23.
Source: CVE Program · Revision 8b16575c39f1e1810c5e863010da073d2d3285e7