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.

Published: 2025-10-13 Last update: 2025-10-20 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2025-62176 is rated Low Risk (23.5/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.06%). Monitor for updates and reassess as exploit intelligence or EPSS changes.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2025-62176

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2025-10-28 0.04% 0.06% +0.01%
2 2025-10-27 0.06% 0.04% -0.01%
3 2025-10-21 — 0.06% —

Full EPSS history (4 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2025-62176

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
4.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:N/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:L)
A normal user session is enough; they don’t have to be admin.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 2.8 1.4 [email protected]

Weakness enumeration for CVE-2025-62176

Affected software / configurations for CVE-2025-62176

Vendor Product Version Raw CPE
joinmastodon mastodon < 4.2.27 cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
joinmastodon mastodon >= 4.3.0, < 4.3.14 cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*
joinmastodon mastodon >= 4.4.0, < 4.4.6 cpe:2.3:a:joinmastodon:mastodon:*:*:*:*:*:*:*:*

References for CVE-2025-62176

cvelogic Threat Intelligence