What is the CVSS score of CVE-2025-27399?

CVE-2025-27399 has a CVSS 3.1 base score of 5.3 (Medium). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N. EPSS exploitation probability: 0.2%.

Which versions of Mastodon are affected by CVE-2025-27399?

Organizations using versions should be aware of moderate risk from CVE-2025-27399, a information exposure vulnerability rated CVSS 5.3. Sensitive information could be exposed to unauthorized parties.. A patch is available.

How to fix or mitigate CVE-2025-27399?

Within 30 days: Identify affected systems running versions and apply vendor patches as part of regular patch cycle. Review data exposure and access controls.

Mastodon CVE-2025-27399

MEDIUM

Information Exposure (CWE-200)

2025-02-27 security-advisories@github.com

Information Disclosure Mastodon

5.3

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

5.3 MEDIUM

AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

Low

Integrity

None

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 28, 2026 - 18:28 vuln.today

Patch released

Mar 28, 2026 - 18:28 nvd

Patch available

CVE Published

Feb 27, 2025 - 18:15 nvd

MEDIUM 5.3

DescriptionGitHub Advisory

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.

AnalysisAI

Mastodon is a self-hosted, federated microblogging platform. Rated medium severity (CVSS 5.3), this vulnerability is remotely exploitable, no authentication required, low attack complexity. This Exposure of Sensitive Information vulnerability could allow attackers to access sensitive data that should not be disclosed.

Technical ContextAI

This vulnerability is classified as Exposure of Sensitive Information (CWE-200), which allows attackers to access sensitive data that should not be disclosed. 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 include: Joinmastodon Mastodon. Version information: prior to 4.1.23.

RemediationAI

A vendor patch is available. Apply the latest security update as soon as possible. Minimize information in error messages, implement proper access controls, encrypt sensitive data at rest and in transit.