Description
Markdown Preview Enhanced is a Markdown preview extension for Visual Studio Code. Prior to 0.8.30, Markdown Preview Enhanced reads repository-controlled .crossnote/head.html content and passes it through resolvePathsInHeader before inserting it into the head of the preview webview document without removing executable content. Script-capable markup executes while the document loads, before the React application and DOMPurify initialize, and can access acquireVsCodeApi to send messages from the webview to the extension host. Opening a Markdown preview in a malicious repository is sufficient to trigger the injected content, and no additional click within the notification or preview is required. This issue is fixed in version 0.8.30.
References8
- github.com/shd101wyy/crossnote/commit/8c55a2ba3365712a1caa4abee…
- github.com/shd101wyy/crossnote/pull/444
- github.com/shd101wyy/crossnote/releases/tag/0.9.31
- github.com/shd101wyy/vscode-markdown-preview-enhanced/commit/8b…
- github.com/shd101wyy/vscode-markdown-preview-enhanced/pull/2323
- github.com/shd101wyy/vscode-markdown-preview-enhanced/releases/…
- github.com/shd101wyy/vscode-markdown-preview-enhanced/security/…
- github.com/shd101wyy/vscode-markdown-preview-enhanced/security/…
Metrics
- CVSS 4.0
-
6.9
MEDIUM
Score source: CNA
CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X - EPSS — exploit probability
- 0% percentile: 23 · as of 11 November 2026
- CWE
- CWE-79
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.