Vulnerability Description
Mastodon is a free, open-source social network server based on ActivityPub. Mastodon 4.3 added notifications of severed relationships, allowing end-users to inspect the relationships they lost as the result of a moderation action. The code allowing users to download lists of severed relationships for a particular event fails to check the owner of the list before returning the lost relationships. Any registered local user can access the list of lost followers and followed users caused by any severance event, and go through all severance events this way. The leaked information does not include the name of the account which has lost follows and followers. This has been fixed in Mastodon v4.3.17, v4.4.11 and v4.5.4.
CVSS Score
MEDIUM
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Joinmastodon | Mastodon | < 4.3.17 |
Related Weaknesses (CWE)
References
- https://github.com/mastodon/mastodon/commit/68e30985ca7afdb89af1b2e9dc962e1993dcPatch
- https://github.com/mastodon/mastodon/commit/b2bcd34486fd6681cc0f30028086ef0f4728Patch
- https://github.com/mastodon/mastodon/commit/c1fb6893c5175d74c074f6f786d504c8bc61Patch
- https://github.com/mastodon/mastodon/security/advisories/GHSA-ww85-x9cp-5v24Third Party Advisory
FAQ
What is CVE-2026-22246?
CVE-2026-22246 is a vulnerability with a CVSS score of 6.5 (MEDIUM). Mastodon is a free, open-source social network server based on ActivityPub. Mastodon 4.3 added notifications of severed relationships, allowing end-users to inspect the relationships they lost as the ...
How severe is CVE-2026-22246?
CVE-2026-22246 has been rated MEDIUM with a CVSS base score of 6.5/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-22246?
Check the references section above for vendor advisories and patch information. Affected products include: Joinmastodon Mastodon.