CVE-2026-66395Public exploitNetwork attack vector

OS command execution via unescaped deep-link plugin name

Published Jul 27, 2026 · Updated Jul 27, 2026

Reflected XSS in SiYuan desktop before 3.7.2 allows remote attackers to execute OS commands through a crafted siyuan:// deep link. The bazaar readme path decodes the plugin-name segment and passes it unescaped through showMessage to insertAdjacentHTML in an Electron renderer with Node.js integration. Execution requires the user to accept the deep link and marketplace trust to be enabled, and commands run with the user's operating-system privileges.

CVSS severity9.6
Critical
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in SiYuan desktop before 3.7.2 allows remote attackers to execute OS commands through a crafted siyuan:// deep link. The bazaar readme path decodes the plugin-name segment and passes it unescaped through showMessage to insertAdjacentHTML in an Electron renderer with Node.js integration. Execution requires the user to accept the deep link and marketplace trust to be enabled, and commands run with the user's operating-system privileges.

The record

CVE
CVE-2026-66395
Published
Jul 27, 2026
Updated
Jul 27, 2026
Vendor
SiYuan Note
Product
SiYuan
Classifications
CWE-1188, CWE-79, T1204.001
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Jul 27, 2026CVE publishedPublication date reported by the CVE source.
  2. Jul 27, 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.

  1. Affected versionversion=0 <3.7.2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

SiYuan Note · SiYuanversion=0 <3.7.2

Published CVSS scores

9.6GitHub Security AdvisoryCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-1188Initialization of a Resource with an Insecure Default
CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
T1204.001Malicious Link

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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