Executive Summary

CVE-2026-36576 is an OS command injection vulnerability found in the app.py component of the openlabs docker-wkhtmltopdf-aas project. The vulnerability allows attackers to execute arbitrary commands on the server by sending a specially crafted POST request.

The root cause is improper handling of user-supplied options in JSON POST requests. These options are concatenated directly into a shell command without validation or sanitization, enabling attackers to inject malicious shell commands using techniques like command substitution or command chaining.

Exploitation can lead to full remote code execution as root, allowing attackers to run any command on the server hosting the service.

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Impact Analysis

This vulnerability can have severe impacts including unauthorized remote code execution with root privileges on the server running the docker-wkhtmltopdf-aas service.

• Attackers can execute arbitrary commands, potentially leading to data exfiltration.
• It can allow attackers to gain reverse shell access, giving them persistent control over the system.
• If the container runs with elevated privileges, attackers might escape the container and compromise the host system.
• Overall, this can lead to full system compromise, loss of data confidentiality, integrity, and availability.

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Detection Guidance

This vulnerability can be detected by monitoring for suspicious POST requests sent to the docker-wkhtmltopdf-aas service, especially those containing crafted JSON payloads with malicious wkhtmltopdf options that could lead to command injection.

You can check if the vulnerable service is running by identifying the docker container exposing the wkhtmltopdf web service, typically on port 80.

• Use Docker commands to list running containers and their ports: `docker ps` and `docker port <container_id>`.
• Capture and inspect HTTP POST requests to the service using network monitoring tools like tcpdump or Wireshark filtering on the container's port.
• Look for POST requests with JSON bodies containing unusual or suspicious wkhtmltopdf options or shell command characters such as `$()`, `;`, or `&&`.
• Example curl command to test the service (use with caution in a controlled environment): `curl -X POST http://<host>:<port>/ -H 'Content-Type: application/json' -d '{"html": "PGh0bWw+PC9odG1sPg==", "margin-top": "0; id"}'` This attempts to inject a command via the margin-top option.

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Mitigation Strategies

Immediate mitigation steps include stopping the vulnerable docker-wkhtmltopdf-aas service to prevent exploitation.

Avoid exposing the vulnerable service to untrusted networks or the internet.

If you must continue using the service, restrict access to trusted users and networks only.

Apply remediation by replacing the vulnerable command execution method in app.py with a safer subprocess.run() call using a list of arguments instead of shell command strings.

Implement strict validation and an allowlist of permitted wkhtmltopdf options to prevent injection of arbitrary commands.

Monitor for any signs of compromise such as unexpected processes or network connections from the host running the service.

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Compliance Impact

The vulnerability allows unauthenticated remote attackers to execute arbitrary OS commands as root on the server, potentially leading to full remote code execution, data exfiltration, and container escape.

Such unauthorized access and potential data breaches could compromise the confidentiality and integrity of sensitive data processed by the application, which may impact compliance with standards and regulations like GDPR and HIPAA that require protection of personal and health information.

However, the provided information does not explicitly discuss compliance impacts or specific regulatory considerations.

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