CVE-2026-47746 misskey-dev CVE debrief

Who should care

Defenders responsible for Misskey installations, security teams, and administrators should be aware of this vulnerability and take necessary actions to prevent potential fraudulent activities. They should prioritize verifying and applying the patch to prevent potential fraudulent activities. The vulnerability affects Misskey installations that have not been updated to version 2026.5.4 or later.

Why it matters

CVE-2026-47746 is a timing attack vulnerability in the Misskey social media platform that allows fraudulent activities to be accepted as valid, leading to a loss of integrity. Defenders should prioritize verifying and applying the patch to prevent potential fraudulent activities.

• Potential loss of integrity due to fraudulent activities
• Need to verify and apply patches to prevent exploitation
• Potential impact on Misskey installations that have not been updated to version 2026.5.4 or later
• Requires review and update of Misskey installations to prevent potential timing attacks

Technical summary

The Misskey social media platform is vulnerable to timing attacks during JSON-LD signature validation and compaction process in versions 12.37.0 and later, but prior to 2026.5.4. This allows an attacker to have fraudulent activities accepted as valid, leading to a loss of integrity. The vulnerability affects Misskey installations that have not been updated to version 2026.5.4 or later. Defenders should prioritize verifying and applying the patch to prevent potential fraudulent activities. The patch is available in version 2026.5.4.

Defensive priority

Defenders should prioritize verifying and applying the patch to prevent potential fraudulent activities.

Recommended defensive actions

• Verify and apply the patch to prevent potential fraudulent activities
• Review and update Misskey installations to version 2026.5.4 or later
• Monitor for suspicious activity related to JSON-LD signature validation and compaction process
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up
• Review compensating controls for exposed systems while remediation is scheduled and verified
• Check relevant monitoring, detection, and logs for exposed assets that need extra review
• Track exceptions, retest remediated assets, and close the item only after evidence is documented

Evidence notes

Evidence from official sources indicates a timing attack vulnerability in Misskey versions 12.37.0 and later, but prior to 2026.5.4. The vulnerability allows fraudulent activities to be accepted as valid, leading to a loss of integrity. Defenders should prioritize verifying and applying the patch to prevent potential fraudulent activities. The patch is available in version 2026.5.4. The vulnerability affects Misskey installations that have not been updated to version 2026.5.4 or later.

Sources and references

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.