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VulnerabilityPublished

CVE-2026-39846: siyuan · Cross-site Scripting

Affects siyuanSource CVE Database V5

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Not known to be exploited · CVSS 9.1 Critical : upgrade to 3.6.4 as a priority.

Data as of 30 Oct 2026, 11:52 UTC

CVSS 3.1 base score
9.1Critical
How severe the flaw is on the 0–10 CVSS scale.

Contested

Critical score, yet low EPSS after six months
EPSS
0.5% chance of exploitation in 30 days – higher than 45% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 3.6.4
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 7 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

What to do

Upgrade siyuan and siyuan-note/siyuan to 3.6.4.

Affected software

ProductAffectedFixed in
siyuan-notesiyuanAffected
  • <3.6.4
Fixed in
  • 3.6.4
GitHubsiyuan-note/siyuanpkg:github/siyuan-note/siyuanOther threatsAffected
  • <3.6.4
Fixed in
  • 3.6.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

Upgrade SiYuan to version 3.6.4 or later, where this vulnerability is fixed. No other mitigation or workaround is documented. Users running affected versions should apply the official update promptly to eliminate the risk of remote code execution via malicious synced notes.

Description

CVE-2026-39846 is a critical stored cross-site scripting (XSS) vulnerability in SiYuan personal knowledge management system versions prior to 3.6.4. The flaw arises from unsafe handling of table caption content, which is stored without proper escaping and later rendered as unescaped HTML. Because the SiYuan Electron desktop client runs with nodeIntegration enabled and contextIsolation disabled, this allows attacker-controlled JavaScript to execute with full access to Node.js APIs, effectively enabling remote code execution. An attacker can exploit this by syncing a crafted malicious note to a victim's workspace, triggering code execution when the victim opens the note. This vulnerability is fixed in version 3.6.4.

References

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