CVE-2026-47746
HighCVSS 8.9Exploitation Probability (EPSS)
Low risk8th percentile - higher than 8% of all known CVEs
Summary
Misskey, an open-source federated social media platform, versions 12.37.0 through 2026.5.4, is vulnerable to timing attacks during JSON-LD signature validation and compaction. Lack of shared JSON-LD parsing context between signature verification and processing leads to a TOCTOU flaw, allowing an attacker to have fraudulent activities accepted as valid. Fixed in version 2026.5.4.
Risk Assessment
An attacker can forge activities on the social network, leading to loss of data integrity and user trust.
Recommendation
Update Misskey to version 2026.5.4 or later.
Other vulnerabilities in Misskey
See all- CVE-2026-46713Critical
Misskey, an open source federated social media platform, has a vulnerability in the JSON-LD signature validation and compaction process that allows spoofed activities to be accepted as valid.
- CVE-2026-48115Medium
Misskey versions from 2024.5.0 up to 2026.5.4 (pre-patch) contain a vulnerability in the Server Announcements API where insufficient permission checks allow attackers to access limited portions of data they normally couldn't view. This vulnerability occurs whether or not federation is enabled.
- CVE-2026-46714Medium
Misskey versions from 8.63.0 up to 2026.5.4 (pre-patch) contain a vulnerability that can cause the web client to slow down or crash when it applies a malformed theme.
- CVE-2026-46712Low
Misskey versions 2025.3.2 up to (but not including) 2026.5.4 have a missing permission check that allows access to certain Direct Messages data regardless of account permissions. Notes with 'specified' visibility are not affected. Fixed in version 2026.5.4.
- CVE-2026-57575Medium
Misskey prior to version 2026.6.0 contains a Server-Side Request Forgery (SSRF) vulnerability in the URL preview functionality. Missing network restrictions before establishing outbound connections allow a remote attacker to send HTTP requests to loopback, private, or link-local services.
- CVE-2026-57574High
Misskey prior to version 2026.6.0 contains a vulnerability in TOTP authentication where insufficient validation of used tokens allows reuse of a single-use code within its valid time step. An attacker who obtains both credentials and a TOTP code can reuse it for unauthorized actions, potentially leading to account takeover.
Original NVD description (English source)
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.