CVE-2026-54702
HighCVSS 7.3Summary
Markdown Preview Enhanced, a Markdown preview extension for Visual Studio Code, prior to 0.8.30 does not validate the command value or arguments sent from the webview. JavaScript running in the preview can invoke privileged extension commands, including file modification, code execution, export-tool execution, and arbitrary URL opening. Exploitation requires a separate webview JavaScript execution path, such as the .crossnote/head.html injection.
Risk Assessment
An attacker could cause file modification, code execution, or opening of malicious URLs with the extension's privileges, potentially compromising the development environment.
Recommendation
Update Markdown Preview Enhanced to version 0.8.30 or later and avoid opening untrusted repositories in VS Code.
Other vulnerabilities in Markdown Preview Enhanced
See all- CVE-2026-54566High
Markdown Preview Enhanced, a Markdown preview extension for Visual Studio Code, prior to 0.8.29 evaluates repository-controlled .crossnote/config.js and .crossnote/parser.js files with vm.runInNewContext, which does not provide a security boundary from the Node.js host realm. Opening a Markdown file in a malicious repository automatically loads these files, and prototype-chain traversal can reach the host Function constructor and process object, allowing OS command execution as the victim account without further interaction.
- CVE-2026-54525High
Markdown Preview Enhanced, a Markdown preview extension for Visual Studio Code, prior to 0.8.28 passes a decoded, Markdown-controlled link target to a Windows file-opening helper that invokes child_process.exec with the start command. When a Windows user opens an untrusted Markdown file and clicks a crafted link, shell metacharacters in the decoded target are interpreted by cmd.exe as command separators, allowing an attacker-selected command to run with the privileges of the current VS Code user.
- CVE-2026-11422High
Markdown Preview Enhanced 0.8.x with crossnote engine 0.9.28 has a code injection vulnerability in the WaveDrom rendering pipeline. Attackers can embed malicious content in a wavedrom fenced code block, leading to arbitrary JavaScript execution in the VS Code webview context and arbitrary file writes on the local filesystem.
Original NVD description (English source)
Markdown Preview Enhanced is a Markdown preview extension for Visual Studio Code. Prior to 0.8.30, the webview message handler in src/preview-provider.ts accepts an attacker-controlled command value and attacker-controlled args, constructs a command in the _crossnote namespace, and invokes vscode.commands.executeCommand without an allowlist or type validation. JavaScript already executing in the preview webview can use this bridge to invoke privileged extension commands, including file modification, code-chunk execution, export-tool execution, and arbitrary URL opening, with attacker-selected arguments. Exploitation requires a separate webview JavaScript execution path, such as the independently tracked .crossnote/head.html injection, but no further authorization check protects the extension-host command boundary. This issue is fixed in version 0.8.30.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS