CVE-2026-13323
MediumCVSS 4.1Exploitation Probability (EPSS)
Low risk7th percentile — higher than 7% of all known CVEs
Summary
In Open VSX Registry before version 1.0.2, the /vscode/unpkg/ endpoint serves user-supplied HTML files with Content-Type: text/html and without Content-Security-Policy or Content-Disposition: attachment headers. An unauthenticated attacker can register a publisher account, upload a VSIX with a crafted HTML payload, and trick an authenticated user into visiting the resulting URL.
Risk Assessment
The risk includes session token exfiltration, generation of persistent Personal Access Tokens (PATs), and unauthorized publication of malicious extension versions. Since Open VSX extensions are distributed to editors like VS Code, VSCodium, Cursor, and Windsurf, a compromised extension update constitutes a supply chain attack against all downstream users.
Recommendation
Upgrade Open VSX Registry to version 1.0.2 or later immediately. As a temporary measure, deploy WAF rules to block the /vscode/unpkg/ endpoint for untrusted content and add the Content-Disposition: attachment header for HTML files.
Original NVD description (English source)
In Open VSX Registry before 1.0.2, the /vscode/unpkg/ endpoint serves user-supplied HTML files with Content-Type: text/html and without a Content-Security-Policy or Content-Disposition: attachment response header. An unauthenticated attacker can register a publisher account, upload a VSIX containing a crafted HTML payload, and induce an authenticated user to visit the resulting URL. The browser renders the file inline in the open-vsx.org origin context, enabling session token exfiltration, persistent Personal Access Token (PAT) generation, and unauthorized publication of malicious extension versions. Because Open VSX extensions are distributed to VS Code, VSCodium, Cursor, Windsurf, and compatible editors, a compromised extension update constitutes a supply chain attack against all downstream users.