What’s Vulnerable › Vulnerabilities

CVE-2026-47746: Misskey: JSON-LD signature validation + compaction is vulnerable to timing attacks

• Severity: high (CVSS 8.9 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-367

Description

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, < 2026.5.4

References

• https://github.com/misskey-dev/misskey/releases/tag/2026.5.4
• https://github.com/misskey-dev/misskey/security/advisories/GHSA-38jx-423m-g387

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