Vulnerability · Published Mar 9, 2026 · Assigned by GitHub_M

CVE-2026-28431Misskey lacks proper authorization checks and input validation

Critical 9.2

In plain English

A critical-severity security flaw in misskey from misskey-dev. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities).

Severity (CVSS 4.0)9.2Critical

Exploit odds (30 days)0.3%top 79.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

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.

Affected products (as reported)

Vendor	Product	Versions
misskey-dev	misskey	>= 8.45.0, < 2026.3.1

Weakness: CWE-285 · Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:N/VA:N/SC:H/SI:N/SA:N

References

https://github.com/misskey-dev/misskey/security/advisories/GHSA-r33c-qg3g-v9cr x_refsource_CONFIRM