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CVE PROGRAM SOURCE RECORD5.3 Medium

CVE-2026-46349

Mastodon: LD-Signature Bypass via JSON-LD Named-Graph Restructuring

Description

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.

Affected products

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

mastodon mastodon

  • >= 4.5.0-beta.1, < 4.5.10affected

References