Executive Summary

CVE-2026-26216 is a critical remote code execution vulnerability in Crawl4AI versions prior to 0.8.0. It exists in the Docker API deployment, specifically in the /crawl endpoint, which accepts a hooks parameter containing Python code executed via the exec() function.

The vulnerability arises because the __import__ builtin function is included in the allowed builtins, allowing unauthenticated remote attackers to import arbitrary Python modules and execute system commands without any authentication.

This flaw enables attackers to execute arbitrary commands, read and write files, exfiltrate sensitive data, and move laterally within internal networks, leading to full server compromise.

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Impact Analysis

Successful exploitation of this vulnerability allows an attacker to fully compromise the affected server.

• Execute arbitrary system commands remotely without authentication.
• Read and write files on the server, potentially modifying or stealing data.
• Exfiltrate sensitive information such as environment variables and API keys.
• Perform lateral movement within internal networks to compromise additional systems.

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Compliance Impact

I don't know

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Detection Guidance

[{'type': 'paragraph', 'content': 'This vulnerability can be detected by monitoring for unauthorized or suspicious POST requests to the /crawl endpoint of the Crawl4AI Docker API deployment. Specifically, look for requests containing the hooks parameter with embedded Python code, which may include usage of the __import__ builtin or system command executions.'}, {'type': 'paragraph', 'content': 'A practical detection method is to inspect network traffic or server logs for POST requests similar to the following payload pattern:'}, {'type': 'list_item', 'content': 'POST /crawl with JSON body containing a hooks parameter with Python code, e.g., { "hooks": { "code": { "on_page_context_created": "async def hook(page, context, **kwargs):\\n __import__(\'os\').system(\'malicious_command\')\\n return page" } } }'}, {'type': 'paragraph', 'content': 'Commands to detect such activity might include searching server access logs for POST requests to /crawl or scanning for suspicious payloads containing __import__ or exec usage.'}, {'type': 'list_item', 'content': "Example command to search logs: grep -i 'POST /crawl' /var/log/nginx/access.log | grep -i '__import__'"}, {'type': 'list_item', 'content': 'Network monitoring tools or intrusion detection systems can be configured to alert on HTTP POST requests to /crawl containing suspicious Python code patterns.'}] [2]

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Mitigation Strategies

Immediate mitigation steps include upgrading Crawl4AI to version 0.8.0 or later, where the vulnerability is fixed by removing the __import__ builtin from allowed builtins and disabling hooks by default.

• Upgrade Crawl4AI to version 0.8.0 or newer.
• Disable hooks by setting the environment variable CRAWL4AI_HOOKS_ENABLED=false to prevent execution of arbitrary code.
• Temporarily disable the Docker API if possible to prevent exploitation.
• Block access to the /crawl endpoint at the network level using firewall rules or reverse proxy configurations.
• Add authentication mechanisms to the API to restrict access.

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