CVSS 3.1
5.3 mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:NCVE-2025-27399
Medium (5.3) in joinmastodon mastodon. EPSS 0.4% chance of exploitation in the next 30 days.
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.
Severity
- EPSS
- 0.4% chance of exploitation in the next 30 days; higher than 29% of CVEs (scores of 2026-10-31)
- CWEs
- CWE-200, CWE-285
- Published
- Modified
- Record from
- the NVD, synced
Affected
- joinmastodon:mastodon
References
- https://github.com/mastodon/mastodon/blob/93f0427b8a84faf68d5d02cdf9a26f98fae16f2b/app/controllers/api/v1/instances/domain_blocks_controller.rb#L33-L35
- https://github.com/mastodon/mastodon/blob/93f0427b8a84faf68d5d02cdf9a26f98fae16f2b/app/controllers/api/v1/instances/domain_blocks_controller.rb#L49-L51
- https://github.com/mastodon/mastodon/commit/6b519cfefa93a923b19d0f20c292c7185f8fd5f5
- https://github.com/mastodon/mastodon/security/advisories/GHSA-94h4-fj37-c825