CVE-2025-62176: Mastadon streaming server allows OAuth clients without the `read` scope to subscribe to public channels
Mastodon is a free, open-source social network server based on ActivityPub. In Mastodon before 4.4.6, 4.3.14, and 4.2.27, the streaming server accepts serving events for public timelines to clients using any valid authentication token, even if those tokens lack the read:statuses scope. This allows OAuth clients without the read scope to subscribe to public channels and receive public timeline events. The impact is limited, as this only affects new public posts published on the public timelines and requires an otherwise valid token, but this may lead to unexpected access to public posts in a limited-federation setting. This issue has been patched in versions 4.4.6, 4.3.14, and 4.2.27. No known workarounds exist.
Affected Software
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Event History
Frequently Asked Questions
What is the severity of CVE-2025-62176?
CVE-2025-62176 is classified as a moderate severity vulnerability due to its potential exposure of sensitive user data.
How do I fix CVE-2025-62176?
To fix CVE-2025-62176, upgrade your Mastodon installation to version 4.4.6 or later, or to version 4.3.14 or 4.2.27.
What vulnerability does CVE-2025-62176 exploit?
CVE-2025-62176 exploits the streaming server in Mastodon that improperly accepts events for public timelines with any valid authentication token.
Who is affected by CVE-2025-62176?
CVE-2025-62176 affects Mastodon users running versions prior to 4.4.6, 4.3.14, or 4.2.27.
What types of tokens are improperly accepted in CVE-2025-62176?
CVE-2025-62176 concerns the acceptance of any valid authentication token lacking the read:statuses scope for public timelines.