Visibility Flaw in Mastodon Microblogging Platform Allows Unauthorized Access to Block Reasons
CVE-2025-27399

5.3MEDIUM

Key Information:

Vendor

Mastodon

Status
Mastodon
Vendor
CVE Published:
27 February 2025

What is CVE-2025-27399?

Mastodon, a popular self-hosted microblogging platform, has a visibility exposure issue affecting versions before 4.1.23, 4.2.16, and 4.3.4. In instances where the visibility setting for domain blocks is configured to display reasons to logged-in users, unapproved users are still able to see these block reasons. This poses a significant privacy risk for instance administrators who wish to keep block reasons confidential. Upgrading to the specified versions will mitigate this issue and enhance user privacy on the platform.

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Affected Version(s)

mastodon < 4.1.23 < 4.1.23

mastodon >= 4.2.0, < 4.2.16 < 4.2.0, 4.2.16

mastodon >= 4.3.0, < 4.3.4 < 4.3.0, 4.3.4

References

https://github.com/mastodon/mastodon/security/advisories/...
x_refsource_CONFIRM
https://github.com/mastodon/mastodon/commit/6b519cfefa93a...
x_refsource_MISC
https://github.com/mastodon/mastodon/blob/93f0427b8a84faf...
x_refsource_MISC

CVSS V3.1

Score:
5.3
Severity:
MEDIUM
Confidentiality:
Low
Integrity:
None
Availability:
Low
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Unchanged

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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