Code execution via synced table-caption stored XSS
Published Apr 7, 2026 · Updated Apr 7, 2026
Stored XSS in SiYuan before 3.6.4 allows remote authenticated users to execute code when a synced malicious note is opened. The table-caption parsing path stores the caption attribute without safe HTML escaping, then unescapes it directly into rendered DOM content. Exploitation requires access to a shared sync target and a victim opening the note; enabled nodeIntegration and disabled contextIsolation expose Node.js APIs in the victim's session.
Summary
What happened
Stored XSS in SiYuan before 3.6.4 allows remote authenticated users to execute code when a synced malicious note is opened. The table-caption parsing path stores the caption attribute without safe HTML escaping, then unescapes it directly into rendered DOM content. Exploitation requires access to a shared sync target and a victim opening the note; enabled nodeIntegration and disabled contextIsolation expose Node.js APIs in the victim's session.
The record
- CVE
- CVE-2026-39846
- Published
- Apr 7, 2026
- Updated
- Apr 7, 2026
- Vendor
- SiYuan Note
- Product
- SiYuan
- Classifications
- CWE-79, CWE-94, T1059.007, T1204.002
- Attack vector
- network
- Privileges
- authenticated
Timeline
How it unfolded
- Apr 7, 2026CVE publishedPublication date reported by the CVE source.
- Apr 7, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=< 3.6.4
What conditions does exploitation require?
What is affected?
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Synced table-caption XSS and RCE proof of conceptproof of concept · demonstrated
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Technologies
Your stack
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Your stack
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