CVE-2026-22246 Local Mastodon users can enumerate and access severed relationships of every other local user
Local users can enumerate and access severed relationship lists of other users due to missing ownership checks, leaking private social graph data.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-22246?
CVE-2026-22246 is a medium-severity vulnerability in mastodon, published on 8 Jan 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Weakness: CWE-201
Which versions are affected by CVE-2026-22246?
1 open source package ship an affected version, including mastodon. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
mastodon Bitnami | All versions | 4.3.17, 4.4.11, 4.5.4 |
Products include Joinmastodon Mastodon.
How do I fix CVE-2026-22246?
Upgrade mastodon to a fixed version for your release line: 4.3.17, 4.4.11 or 4.5.4.
Is CVE-2026-22246 being exploited?
There is no known exploitation of CVE-2026-22246 in the wild and no public exploit code.
Other vulnerabilities in mastodon
- CVE-2023-36460 Mastodon vulnerable to arbitrary file creation through media attachments
- CVE-2022-2166 Improper Restriction of Excessive Authentication Attempts in mastodon/mastodon
- CVE-2022-24307 Missing authorization in n/a
- CVE-2018-21018 Auth bypass in n/a
- CVE-2024-23832 Mastodon Remote user impersonation and takeover
Sources
Also known as BIT-mastodon-2026-22246, GHSA-ww85-x9cp-5v24.