Quick answers
- Is CVE-2026-46349 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-46349 being exploited in the wild.
- How severe is CVE-2026-46349?
- Medium severity, with a CVSS score of 5.3, published 24 June 2026.
- Which products and versions are affected?
- Mastodon < 4.5.10, < 4.4.17, < 4.3.23.
- Is there a fix for CVE-2026-46349?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-46349 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-46349?
- Check whether you run Mastodon at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
A signature verification bypass exists in Mastodon's handling of JSON-LD activities signed with Linked-Data Signatures (CWE-347). The root cause is insufficient protection during the normalization process, which allows an attacker to restructure a validly signed activity from a third party. By re-arranging the named-graph structure of the JSON-LD data, an attacker can force the server to process the activity differently than intended, such as re-issuing retracted 'Announce' (boost) activities. This is a network-reachable vulnerability requiring no authentication or user interaction. Patches are available in versions 4.5.10, 4.4.17, and 4.3.23.
Affected products
- Mastodon Mastodon < 4.5.10, < 4.4.17, < 4.3.23
Timeline
- 2026-05-20: advisory: Initial GitHub advisory published
- 2026-06-24: disclosed: CVE published to NVD