What is the CVSS score of CVE-2026-28431?

CVE-2026-28431 has a CVSS 3.1 base score of 7.5 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. EPSS exploitation probability: 0.0%.

Which versions of Misskey are affected by CVE-2026-28431?

A high-severity vulnerability (CVE-2026-28431) has been identified in Misskey, an open-source federated social media platform, with a CVSS score of 7.5.

How to fix or mitigate CVE-2026-28431?

Within 24 hours: Inventory all Misskey deployments and assess whether they are internet-facing or internally used; isolate critical instances if possible and review access logs for suspicious activity. Within 7 days: Implement network segmentation and access controls to limit Misskey exposure; establish monitoring for exploitation attempts; contact Misskey security team for patch timeline and subscribe to security advisories. Within 30 days: Develop and execute a patching strategy immediately upon vendor patch release; conduct security assessment of affected systems; document all compensating controls in place.

Misskey CVE-2026-28431

HIGH

Improper Authorization (CWE-285)

2026-03-10 security-advisories@github.com

Authentication Bypass Misskey

7.5

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

7.5 HIGH

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

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

CVSS VectorGitHub Advisory

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:55 vuln.today

CVE Published

Mar 10, 2026 - 07:43 nvd

HIGH 7.5

DescriptionGitHub Advisory

Misskey is an open source, federated social media platform. All Misskey servers running versions 8.45.0 and later, but prior to 2026.3.1, contain a vulnerability that allows bad actors access to data that they ordinarily wouldn't be able to access due to insufficient permission checks and proper input validation. This vulnerability occurs regardless of whether federation is enabled or not. This vulnerability could lead to a significant data breach. This vulnerability is fixed in 2026.3.1.

AnalysisAI

Misskey is an open source, federated social media platform.

Technical ContextAI

Classified as CWE-285 (Improper Authorization). Affects but. Misskey is an open source, federated social media platform. All Misskey servers running versions 8.45.0 and later, but prior to 2026.3.1, contain a vulnerability that allows bad actors access to data that they ordinarily wouldn't be able to access due to insufficient permission checks and proper input validation. This vulnerability occurs regardless of whether federation is enabled or not. This vulnerability could lead to a significant data breach. This vulnerability is fixed in 2026.3.1.