Executive brief
Crawl4AI, an open-source web crawling and scraping tool, contains a security flaw in its Docker API server. An attacker can remotely execute custom JavaScript code within the server's browser environment. This could allow an unauthorized user to access internal network services or sensitive data that should otherwise be protected.
Technical details
A code injection vulnerability (CWE-94) exists in the /execute_js endpoint of the Crawl4AI Docker API server. The endpoint accepts and executes user-supplied JavaScript in the server's browser context. Because the browser is launched with the '--disable-web-security' flag enabled by default, an attacker can bypass the Same-Origin Policy (SOP). This allows for arbitrary JavaScript execution and Server-Side Request Forgery (SSRF) against internal services and cloud metadata endpoints. The vulnerability is addressed in version 0.8.7 by disabling the endpoint by default, removing the insecure browser flag, and implementing a destination URL blocklist.
Affected products
- Crawl4AI Crawl4AI < 0.8.7
Timeline
- 2026-06-02: advisory: Vendor security advisory published (GHSA-365w-hqf6-vxfg)
- 2026-06-30: disclosed: CVE-2026-56264 published to NVD