Vulnerability · Published Aug 3, 2026 · Assigned by GitHub_M
CVE-2026-47746Misskey: JSON-LD signature validation + compaction is vulnerable to timing attacks
High 8.9
In plain English
A high-severity security flaw in misskey from misskey-dev. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 21% of all known vulnerabilities).
Official 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 (as reported)
| Vendor | Product | Versions |
|---|---|---|
| misskey-dev | misskey | >= 12.37.0, < 2026.5.4 |
Weakness: CWE-367 · Vector: CVSS:4.0/AV:N/AC:H/AT:N/PR:N/UI:N/VC:N/VI:H/VA:N/SC:N/SI:H/SA:N
References
- https://github.com/misskey-dev/misskey/security/advisories/GHSA-38jx-423m-g387 x_refsource_CONFIRM
- https://github.com/misskey-dev/misskey/releases/tag/2026.5.4 x_refsource_MISC