CVE-2026-46349

MEDIUM

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

Title source: cna
STIX 2.1

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.

References (1)

Core 1
Core References

Scores

CVSS v3 5.3
EPSS 0.0016
EPSS Percentile 5.9%
Attack Vector NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

CISA SSVC

Vulnrichment
Exploitation none
Automatable yes
Technical Impact partial

Details

CWE
CWE-347
Status published
Products (1)
mastodon/mastodon >= 4.5.0-beta.1, < 4.5.10
Published Jun 24, 2026
Tracked Since Jun 25, 2026