---
title: "CVE-2026-100643: SiYuan - Stored XSS & Remote Code Execution"
description: "SiYuan < v3.8.4 contains a stored XSS caused by improper escaping of Attribute View values in textarea elements, letting authenticated attackers execute JavaScript and potentially commands in Electron app, exploit requires authentication."
url: https://panop.io/threat-heartbeat/CVE-2026-100643/
---

# CVE-2026-100643 SiYuan - Stored XSS & Remote Code Execution

SiYuan < v3.8.4 contains a stored XSS caused by improper escaping of Attribute View values in textarea elements, letting authenticated attackers execute JavaScript and potentially commands in Electron app, exploit requires authentication.

CVSS base score 8.0 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

EPSS

0.42% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-100643)

## Details

Type

Stored XSS

Impact

Remote Code Execution, Stored XSS

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H

Published

26 September 2026

Updated

15 October 2026

Weakness

[CWE-79](https://cwe.mitre.org/data/definitions/79.html)

## Vendor fix

Update to version v3.8.4 or later.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

## References

- [https://nvd.nist.gov/vuln/detail/CVE-2026-100643](https://nvd.nist.gov/vuln/detail/CVE-2026-100643)
- [https://github.com/siyuan-note/siyuan/security/advisories/GHSA-h3p6-c22r-fx2j](https://github.com/siyuan-note/siyuan/security/advisories/GHSA-h3p6-c22r-fx2j)
- [https://www.vulncheck.com/advisories/siyuan-before-3.8.4-stored-xss-via-attribute-view-textarea](https://www.vulncheck.com/advisories/siyuan-before-3.8.4-stored-xss-via-attribute-view-textarea)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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