CVE-2026-22246

MEDIUM EPSS 13.5%
Published Jan 8, 20265mo ago · Modified Jun 17, 20261w ago
4.3 CVSS 3.1
Medium
Find Similar
Published Jan 8, 2026 5mo ago
Last Modified Jun 17, 2026 1w ago

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 Details

Base Score
4.3
Exploitability
2.8
Impact
1.4
Vector string
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N
Attack Vector Network
Attack Complexity Low
Privileges Required Low
User Interaction None
Scope Unchanged
Confidentiality Low
Integrity None
Availability None

Threat Intelligence

EPSS Exploit Probability
13.5% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-201

Affected Products 3

VendorProductVersionRange
joinmastodonmastodon* <4.3.17
joinmastodonmastodon*≥4.4.0  –  <4.4.11
joinmastodonmastodon*≥4.5.0  –  <4.5.4

References 4

  • github.com https://github.com/mastodon/mastodon/commit/68e30985ca7afdb89af1b2e9dc962e1993dc8076
    Patch
  • github.com https://github.com/mastodon/mastodon/commit/b2bcd34486fd6681cc0f30028086ef0f47282adf
    Patch
  • github.com https://github.com/mastodon/mastodon/commit/c1fb6893c5175d74c074f6f786d504c8bc610d57
    Patch
  • github.com https://github.com/mastodon/mastodon/security/advisories/GHSA-ww85-x9cp-5v24
    Third Party Advisory

Remediation

  • github.com https://github.com/mastodon/mastodon/commit/68e30985ca7afdb89af1b2e9dc962e1993dc8076
    Patch
  • github.com https://github.com/mastodon/mastodon/commit/b2bcd34486fd6681cc0f30028086ef0f47282adf
    Patch
  • github.com https://github.com/mastodon/mastodon/commit/c1fb6893c5175d74c074f6f786d504c8bc610d57
    Patch