CVE-2026-47746: Misskey-Dev Misskey

High severity, CVSS 8.9. EPSS: 0.3% chance of exploitation in the next 30 days.

Misskey is an open source, federated social media platform. Versions 12.37.0 and later, but prior to 2026.5.4, are vulnerable to timing attacks during JSON-LD signature validation and the compaction process. Because the JSON-LD parsing context is not shared between signature verification and subsequent processing, the application may trust information that should not be trusted, resulting in a time-of-check to time-of-use (TOCTOU) flaw. This allows an attacker to have fraudulent activities accepted as valid, leading to a loss of integrity. This issue has been fixed in version 2026.5.4.

Affected products

• Misskey-Dev Misskey: from 12.37.0, before 2026.5.4 (fixed in 2026.5.4)

Published 2026-08-03. Last modified 2026-09-08.