{"id":"CVE-2026-100639","published":"2026-09-26T14:16:45.633","lastModified":"2026-09-28T19:16:44.720","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.","cvssScore":8.8,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H","cwes":["CWE-79"],"vendors":[],"products":[],"references":[{"url":"https://github.com/siyuan-note/siyuan/security/advisories/GHSA-2cmm-9x9j-rvff","tags":[]},{"url":"https://www.vulncheck.com/advisories/siyuan-before-3.8.4-cross-site-scripting-via-kramdown-ial","tags":[]},{"url":"https://github.com/siyuan-note/siyuan/security/advisories/GHSA-2cmm-9x9j-rvff","tags":[]}],"exploitRefs":[{"url":"https://github.com/siyuan-note/siyuan/security/advisories/GHSA-2cmm-9x9j-rvff","tags":[]},{"url":"https://github.com/siyuan-note/siyuan/security/advisories/GHSA-2cmm-9x9j-rvff","tags":[]}],"hasPoc":true,"ai":{"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.","remediation":"Upgrade to SiYuan v3.8.4 or later.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["rce","web","markdown","html-injection","electron"],"model":"qwen2.5:7b-instruct","analyzedAt":"2026-09-30T09:03:07.882Z"}}