How severe is CVE-2026-28431?

CVE-2026-28431 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.

Is CVE-2026-28431 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-28431?

CVE-2026-28431 affects Misskey. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-28431?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-28431 have an EU (EUVD) identifier?

Yes. CVE-2026-28431 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-10365.

When was CVE-2026-28431 published?

CVE-2026-28431 was published on 2026-03-10 and last updated on 2026-06-17.

CVE-2026-28431

CVE-2026-28431 is a high-severity vulnerability in Misskey with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-285.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 9.2
EPSS exploit prediction: 0% (16th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-10365
Weakness: CWE-285
Affected product: Misskey
Published: 2026-03-10
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-28431?: 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.
How severe is CVE-2026-28431?: CVE-2026-28431 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity none, and availability none.
Is CVE-2026-28431 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (16th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-28431?: CVE-2026-28431 affects Misskey. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-28431?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-28431 have an EU (EUVD) identifier?: Yes. CVE-2026-28431 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-10365.
When was CVE-2026-28431 published?: CVE-2026-28431 was published on 2026-03-10 and last updated on 2026-06-17.

References

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

Affected products (1)

cpe:2.3:a:misskey:misskey:*:*:*:*:*:*:*:*

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