CVE-2026-46349
Mastodon: LD-Signature Bypass via JSON-LD Named-Graph Restructuring
CVSS Score
5.3
EPSS Score
0.0%
EPSS Percentile
0th
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.
| CWE | CWE-347 |
| Vendor | mastodon |
| Product | mastodon |
| Published | Jun 24, 2026 |
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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
Low
Availability
None
Affected Versions
mastodon / mastodon
>= 4.5.0-beta.1, < 4.5.10