CVE-2025-27399

low-risk
Published 2025-02-27

Mastodon is a self-hosted, federated microblogging platform. In versions prior to 4.1.23, 4.2.16, and 4.3.4, when the visibility for domain blocks/reasons is set to "users" (localized English string: "To logged-in users"), users that are not yet approved can view the block reasons. Instance admins that do not want their domain blocks to be public are impacted. Versions 4.1.23, 4.2.16, and 4.3.4 fix the issue.

Do I need to act?

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0.45% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
5
CVSS 5.3/10 Medium
NETWORK / LOW complexity

Affected Products (1)

Affected Vendors

Joinmastodon

References (4)

Product https://github.com/mastodon/mastodon/blob/93f0427b8a84faf68d5d02cdf9a26f98fae16f...
Product https://github.com/mastodon/mastodon/blob/93f0427b8a84faf68d5d02cdf9a26f98fae16f...
Patch https://github.com/mastodon/mastodon/commit/6b519cfefa93a923b19d0f20c292c7185f8f...
Vendor Advisory https://github.com/mastodon/mastodon/security/advisories/GHSA-94h4-fj37-c825
28
/ 100
low-risk
Severity 21/34 · High
Exploitability 2/34 · Minimal
Exposure 5/34 · Minimal