CVE-2026-53755: Kidocode Crawl4ai Server Side Request Forgery (CVSS 8.6)

Crawl4AI before 0.8.7 contains a server-side request forgery (SSRF) vulnerability in the Docker API server's /crawl/job and /llm/job endpoints, which accept webhook URLs without destination validation. An attacker can supply webhook URLs pointing to private or internal IP ranges, Docker networks, or cloud metadata endpoints (e.g. 169.254.169.254), causing the server to make requests to internal services and potentially expose cloud metadata.

Crawl4AI is an open-source LLM friendly web crawler & scraper. Prior to 0.8.7, the _safe_eval_expression() function in the computed fields feature uses an AST validator that only blocks attributes starting with underscore. Python generator and frame object attributes (gi_frame, f_back, f_builtins) do NOT start with underscore, enabling a complete sandbox escape to achieve arbitrary code execution. The attack requires no authentication (JWT disabled by default) and is triggered via POST /crawl with a crafted extraction schema. This vulnerability is fixed in 0.8.7.

Crawl4AI before 0.8.7 contains a server-side request forgery vulnerability in the /crawl, /crawl/stream, /md, and /llm endpoints that fetch arbitrary user-supplied URLs without validation. Unauthenticated attackers can bypass the internal-address blocklist using IPv6-mapped IPv4 addresses to reach internal services and cloud metadata endpoints.

Crawl4AI versions prior to 0.8.0 contain a local file inclusion vulnerability in the Docker API deployment. The /execute_js, /screenshot, /pdf, and /html endpoints accept file:// URLs, allowing unauthenticated remote attackers to read arbitrary files from the server filesystem. An attacker can access sensitive files such as /etc/passwd, /etc/shadow, application configuration files, and environment variables via /proc/self/environ, potentially exposing credentials, API keys, and internal application structure.

FastGPT is an AI Agent building platform. Prior to version 4.14.9.5, the FastGPT HTTP tools testing endpoint (/api/core/app/httpTools/runTool) is exposed without any authentication. This endpoint acts as a full HTTP proxy — it accepts a user-supplied baseUrl, toolPath, HTTP method, custom headers, and body, then makes a server-side HTTP request and returns the complete response to the caller. This issue has been patched in version 4.14.9.5.

FastMCP is a Pythonic way to build MCP servers and clients. Prior to version 3.2.0, the OpenAPIProvider in FastMCP exposes internal APIs to MCP clients by parsing OpenAPI specifications. The RequestDirector class is responsible for constructing HTTP requests to the backend service. A vulnerability exists in the _build_url() method. When an OpenAPI operation defines path parameters (e.g., /api/v1/users/{user_id}), the system directly substitutes parameter values into the URL template string without URL-encoding. Subsequently, urllib.parse.urljoin() resolves the final URL. Since urljoin() interprets ../ sequences as directory traversal, an attacker controlling a path parameter can perform path traversal attacks to escape the intended API prefix and access arbitrary backend endpoints. This results in authenticated SSRF, as requests are sent with the authorization headers configured in the MCP provider. This issue has been patched in version 3.2.0.