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Vulnerability · Published Oct 14, 2026 · Assigned by GitHub_M

CVE-2026-54703Markdown Preview Enhanced: Arbitrary File Write via updateMarkdown Command Without Path Validation

Medium 5.8

In plain English

A medium-severity security flaw in vscode-markdown-preview-enhanced from shd101wyy. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 23% of all known vulnerabilities).

Severity (CVSS 4.0)5.8Medium
Exploit odds (30 days)0.3%top 76.7% of all CVEs
Exploited in the wildNo reportsCISA SSVC: poc
Attack toolingNoneno public tooling known

Official description

Markdown Preview Enhanced is a Markdown preview extension for Visual Studio Code. Prior to 0.8.30, the _crossnote.updateMarkdown command in Markdown Preview Enhanced accepts an arbitrary URI and attacker-controlled content, then passes them to vscode.workspace.fs.writeFile without validating that the target is the Markdown file represented by the current preview. JavaScript already executing in the preview webview can invoke this command through the extension message bridge and write any file permitted by the VS Code user's operating-system privileges, including user configuration, startup, source, and build files. This file-write vulnerability requires a separate webview JavaScript execution path, such as the independently tracked head.html injection and blind command-dispatch weaknesses. This issue is fixed in version 0.8.30.

Affected products (as reported)

VendorProductVersions
shd101wyy vscode-markdown-preview-enhanced < 0.8.30

Weakness: CWE-73 · Vector: CVSS:4.0/AV:L/AC:L/AT:P/PR:N/UI:P/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N

References