CVE-2026-100639

8.8 HIGHpublic exploit available

Published 2026-09-26 · Updated 2026-09-28

AI risk analysis

Summary: The flaw allows an attacker to inject arbitrary attributes into HTML content, leading to potential remote code execution when the affected control receives focus in the SiYuan application.
Exploitability: Exploitation requires pasting a crafted Markdown snippet and focusing the affected gutter control, making it moderately difficult to exploit.
Blast radius: If exploited, the impact could be severe, allowing an attacker to execute arbitrary JavaScript with renderer Node.js privileges in the Electron application.
Detection: No reliable host or network indicator is derivable from the published description.
Prioritized remediation: Upgrade to SiYuan v3.8.4 or later.

rcewebmarkdownhtml-injectionelectron

Analysis generated locally by qwen2.5:7b-instruct (no data left the box). AI-assisted — verify against primary sources before acting.

NVD description

SiYuan v3.8.3 fails to HTML-escape the data-subtype attribute when generating gutter-button markup (app/src/protyle/gutter/button.ts, assigned via innerHTML in app/src/protyle/gutter/index.ts) from content pasted as plain-text Markdown containing a Kramdown inline attribute list (IAL). Because the shared Lute renderer parses Kramdown IAL from text/plain input, an attacker-supplied Markdown snippet using entity-encoded quotes in data-subtype breaks out of the attribute value when the gutter markup is re-parsed by the browser, injecting additional attributes such as autofocus and onfocus. If a victim pastes the crafted Markdown and the affected gutter control receives focus, the injected handler executes; in the Electron desktop application, where the main BrowserWindow enables Node integration and disables context isolation, this results in JavaScript execution with renderer Node.js privileges (remote code execution). Fixed in v3.8.4.

CVSS vector

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

Weaknesses

CWE-79

Public exploit & PoC references

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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