CVE-2026-87814 siyuan-note CVE debrief

Who should care

Defenders responsible for SiYuan deployments should assess exposure and prioritize verification and remediation efforts to prevent potential attacks. This includes verifying the affected product deployments, reviewing the supplied official advisory or CVE record, and restricting workspace access to trusted users. Additionally, defenders should monitor workspace activity for suspicious behavior and track exceptions, retest remediated assets, and close the

Why it matters

CVE-2026-87814 is a stored cross-site scripting vulnerability in SiYuan before v3.8.2, allowing attackers to execute JavaScript in the SiYuan origin when victims preview assets. Defenders should prioritize verifying and upgrading to SiYuan v3.8.2 or later, and restrict workspace access to trusted users.

• Authenticated API requests can be manipulated
• Workspace content can be modified
• JavaScript execution can lead to unauthorized actions

Technical summary

The vulnerability affects the search asset preview feature in SiYuan before v3.8.2, allowing attackers to execute JavaScript in the SiYuan origin when victims preview assets. This is a stored cross-site scripting vulnerability that can lead to unauthorized actions and workspace manipulation. The vulnerability has a CVSS score of 8.4 and is considered HIGH severity. Defenders should prioritize verifying and upgrading to SiYuan v3.8.2 or later, and restrict workspace access to trusted users. The vulnerability was disclosed on 2026-09-09T12:17:16.390Z.

Defensive priority

Defenders should prioritize verifying and upgrading to SiYuan v3.8.2 or later, and restrict workspace access to trusted users.

Recommended defensive actions

• Verify and upgrade to SiYuan v3.8.2 or later
• Restrict workspace access to trusted users
• Monitor workspace activity for suspicious behavior
• 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

The CVE record and NVD entry provide details on the vulnerability, but vendor confirmation and additional details are limited. The vulnerability was disclosed on 2026-09-09T12:17:16.390Z. Defenders should verify the affected product deployments and review the supplied official advisory or CVE record to validate affected scope, severity, and vendor guidance.

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.