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VulnerabilityPublished

CVE-2026-28433: misskey · Insecure Direct Object Reference

Affects misskeySource CVE Database V5

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Not known to be exploited · CVSS 2.3 Low : upgrade to 2026.3.1 when convenient.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 4.0 base score
2.3Low
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.2% chance of exploitation in 30 days – higher than 14% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 2026.3.1
CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 9 Mar 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade misskey and misskey-dev/misskey to 2026.3.1.

Affected software

ProductAffectedFixed in
misskey-devmisskeyAffected
  • >=10.93.0 <2026.3.1
Fixed in
  • 2026.3.1
GitHubmisskey-dev/misskeypkg:github/misskey-dev/misskeyOther threatsAffected
  • >=10.93.0 <2026.3.1
Fixed in
  • 2026.3.1

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Organizations should upgrade all Misskey instances to version 2026.3.1 or later immediately to apply the official patch that enforces proper ownership validation during data import. Until patched, administrators should restrict access to import functionality to trusted users only and monitor logs for suspicious import requests involving unknown file IDs. Implementing additional access controls or rate limiting on import APIs can reduce exploitation risk. It is also advisable to audit existing imported data for unauthorized entries and notify affected users if data exposure is suspected. Federated servers should coordinate to ensure all nodes are updated to prevent cross-server data leakage. Finally, security teams should educate users about the importance of safeguarding file identifiers and credentials to limit information disclosure that could facilitate exploitation.

Description

Misskey is an open source, federated social media platform. All Misskey servers running versions 10.93.0 and later, but prior to 2026.3.1, contain a vulnerability that allows importing other users' data due to lack of ownership validation. The impact of this vulnerability is estimated to be relatively low, as bad actors would require the ID corresponding to the target file for import. This vulnerability is fixed in 2026.3.1.

References

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