CVE-2025-62176

Mastadon streaming server allows OAuth clients without the `read` scope to subscribe to public channels

MEDIUM
4.3
CVSS Score
Published: October 13, 2025 at 09:04 PM UTC
Updated: October 19, 2026 at 04:10 PM UTC
2 products affected across 2 vendorsMastodonMastodon

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Severity
MEDIUM4.3
Exploit prediction
EPSS 0.3%
SSVC
No known exploit

Description

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 4.2.274.3.0 ≤ v < 4.3.144.4.0 ≤ v < 4.4.6
v < 4.2.27
Affected range stops below 4.2.27, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.3.14, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.4.6, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCNo known exploitNot automatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

4.3MEDIUMGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-280

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