CVE-2026-66396Public exploitNetwork attack vectorHinoki check available

Stored XSS to RCE via title-img interpolation

Published Jul 27, 2026 · Updated Jul 27, 2026

Stored XSS in SiYuan before 3.7.2 allows remote authenticated users to execute OS commands via a crafted title-img IAL value. Gallery and Kanban rendering copies the decoded title-img value into CoverURL, interpolates it unescaped into an image style attribute, and inserts the result through innerHTML or outerHTML. Editor permissions are required to plant the stored handler, and code runs with the victim's privileges only when an affected document opens in the Node-enabled Electron desktop renderer.

CVSS severity9.3
Critical
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkAvailable
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Summary

What happened

Stored XSS in SiYuan before 3.7.2 allows remote authenticated users to execute OS commands via a crafted title-img IAL value. Gallery and Kanban rendering copies the decoded title-img value into CoverURL, interpolates it unescaped into an image style attribute, and inserts the result through innerHTML or outerHTML. Editor permissions are required to plant the stored handler, and code runs with the victim's privileges only when an affected document opens in the Node-enabled Electron desktop renderer.

The record

CVE
CVE-2026-66396
Published
Jul 27, 2026
Updated
Jul 27, 2026
Vendor
SiYuan Note
Product
SiYuan
Classifications
CWE-79, CWE-83, CWE-1188, T1059
Attack vector
network
Privileges
authenticated

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

Compare your product and version with the public record. A matching version still requires validation against your environment.

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 privilegesauthenticated

What is affected?

SiYuan Note · SiYuanversion=0 <3.7.2

Published CVSS scores

8.4GitHubCVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:H
9.3VulnCheckCVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:H/VI:H/VA:H/SC:H/SI:H/SA: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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CWE-83Improper Neutralization of Script in Attributes in a Web Page
CWE-1188Initialization of a Resource with an Insecure Default
T1059Command and Scripting Interpreter

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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