CVE-2026-100644 siyuan-note CVE debrief

Who should care

Defenders responsible for SiYuan instances, especially those with public exposure and authentication disabled, should assess and remediate this vulnerability to prevent potential SQL injection attacks.

Why it matters

CVE-2026-100644 is a SQL injection vulnerability in SiYuan before v3.8.4 that allows unauthenticated attackers to extract arbitrary database rows. Defenders should prioritize verification, remediation, and monitoring to prevent potential data extraction and disruption.

• Potential data extraction from database rows across all notebooks
• Possible disruption of SiYuan instance functionality
• Need for verification of instance version and exposure
• Priority for remediation and monitoring of suspicious activity

Technical summary

The SiYuan before v3.8.4 contains a SQL injection vulnerability in the graph query endpoint where the dailyNoteSavePath parameter is concatenated into SQL without escaping. This allows unauthenticated attackers on published sites with auth disabled to inject SQL via UNION SELECT to extract arbitrary database rows from all notebooks. The vulnerability is highly severe with a CVSS score of 8.7, indicating a high level of risk. Defenders should prioritize verifying and remediating this vulnerability, especially for publicly accessible SiYuan instances with authentication disabled.

Defensive priority

Defenders should prioritize verifying and remediating this vulnerability, especially for publicly accessible SiYuan instances with authentication disabled.

Recommended defensive actions

• Verify SiYuan instances for version v3.8.4 or later
• Disable public access to SiYuan instances or ensure authentication is enabled
• Monitor for suspicious SQL injection attempts
• 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
• Confirm whether affected product deployments exist in managed environments and assign an owner for follow-up

Evidence notes

The CVE record and source item provide details on the SQL injection vulnerability in SiYuan before v3.8.4. The vulnerability allows unauthenticated attackers to inject SQL via UNION SELECT to extract arbitrary database rows from all notebooks.

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.