CVE-2026-22246Mastodon is a free, open-source social network server based on ActivityPub.
Updated under an hour ago ()
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It affects joinmastodon mastodon. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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Free account, 1 product
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
- 4.3 MEDIUM (v3.1, NVD)CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
- Weakness (CWE)
- CWE-201
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Not given
- NVD analysis
- Analyzed
- Record last updated
- Jun 17, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
joinmastodon mastodon joinmastodon:mastodon | before 4.3.17; from 4.4.0 before 4.4.11; from 4.5.0 before 4.5.4 | NVD |
References
- https://github.com/mastodon/mastodon/commit/68e30985ca7afdb89af1b2e9dc962e1993dc8076patch
- https://github.com/mastodon/mastodon/commit/b2bcd34486fd6681cc0f30028086ef0f47282adfpatch
- https://github.com/mastodon/mastodon/commit/c1fb6893c5175d74c074f6f786d504c8bc610d57patch
- https://github.com/mastodon/mastodon/security/advisories/GHSA-ww85-x9cp-5v24third-party-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.