medium5.3
CVE-2025-27399
Mastodon is a self-hosted, federated microblogging platform.
Impact
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.
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Joinmastodon | Mastodon | before 4.1.23 from 4.2.0 before 4.2.16 from 4.3.0 before 4.3.4 |
Weakness classification
References
- NVD record
- CVE.org record
- 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