CVE-2025-62175: Mastodon streaming API fails to disconnect disabled and suspended users

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2025-10-13 · updated 2026-10-19
Weakness: CWE-273

Description

Mastodon is a free, open-source social network server based on ActivityPub. In versions before 4.4.6, 4.3.14, and 4.2.27, disabling or suspending a user account does not disconnect the account from the streaming API. This allows disabled or suspended accounts to continue receiving real-time updates through existing streaming connections and to establish new streaming connections, even though they cannot interact with other API endpoints. This undermines moderation actions, as administrators expect disabled or suspended accounts to be fully disconnected from the service. This issue has been patched in versions 4.4.6, 4.3.14, and 4.2.27. No known workarounds exist.

Affected products

mastodon: before 4.2.27; from 4.3.0 before 4.3.14; from 4.4.0 before 4.4.6 — fixed in 4.2.27, 4.3.14, 4.4.6

How to fix

Upgrade to a fixed version: mastodon 4.2.27, 4.3.14, 4.4.6. Check the vendor advisory for mitigations.

References

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