Mastodon: LD-Signature Bypass via JSON-LD Named-Graph Restructuring_CVE-2026-46349

5.3 / 10

MEDIUM

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

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.

Basic Information

ID CVE-2026-46349

Source GitHub_M

Published Jun 24, 2026 at 19:40

Affected Product

Vendor mastodon

Product mastodon

Version >= 4.5.0-beta.1, < 4.5.10

Affected Versions mastodon mastodon >= 4.5.0-beta.1, < 4.5.10

CWE Classification

CWE-347

References

github.com /mastodon/mastodon/security/advisories/GHSA-chgx-jx3p-rf73

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