CVE-2025-27399: 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…

PriorityP427medium5.3CVSS 3.1

AVNACLPRNUINSUCLINAN

EPSS

0.33%

24.7th percentile

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

6 ranges

Vendor	Product	Version range	Fixed in
joinmastodon	mastodon	< 4.1.23	4.1.23
joinmastodon	mastodon	>= 4.2.0 < 4.2.16	4.2.16
joinmastodon	mastodon	>= 4.3.0 < 4.3.4	4.3.4
mastodon	mastodon	< 4.1.23	4.1.23
mastodon	mastodon	—	—
mastodon	mastodon	—	—

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