CVE-2026-46713: Misskey: JSON-LD signature validation + compaction may lead to improper activity handling

Severity: critical (CVSS 9.2 v4.0)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-03 · updated 2026-10-23
Weakness: CWE-347

Description

Misskey is an open source, federated social media platform. Versions 12.37.0 and later, but prior to 2026.5.4, contain a vulnerability in the JSON-LD signature validation and compaction process that allows spoofed activities to be accepted as valid. This issue has been fixed in version 2026.5.4.

Affected products

misskey-dev misskey: from 12.37.0, < 2026.5.4

References

https://github.com/misskey-dev/misskey/releases/tag/2026.5.4
https://github.com/misskey-dev/misskey/security/advisories/GHSA-w8x2-gpq6-jxvf

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