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.
Metrics
Affected Vendors & Products
References
History
Fri, 09 Jan 2026 13:30:00 +0000
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Joinmastodon
Joinmastodon mastodon |
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Joinmastodon
Joinmastodon mastodon |
Thu, 08 Jan 2026 18:15:00 +0000
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ssvc
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Thu, 08 Jan 2026 15:45:00 +0000
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| 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. | |
| Title | Local Mastodon users can enumerate and access severed relationships of every other local user | |
| Weaknesses | CWE-201 | |
| References |
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| Metrics |
cvssV3_1
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Status: PUBLISHED
Assigner: GitHub_M
Published:
Updated: 2026-01-08T15:54:24.770Z
Reserved: 2026-01-07T05:19:12.921Z
Link: CVE-2026-22246
Updated: 2026-01-08T15:52:01.399Z
Status : Awaiting Analysis
Published: 2026-01-08T16:16:02.957
Modified: 2026-01-08T18:08:18.457
Link: CVE-2026-22246
No data.
OpenCVE Enrichment
Updated: 2026-01-09T13:24:44Z