browser-use Web UI LLM API Key Exposure via Cleartext Storage

Executive Summary

CVE-2026-82640 is a vulnerability in browser-use web-ui versions 2.0.0 through 3.0.0 where LLM API keys are stored in cleartext on disk without encryption or access restrictions. The application writes these keys to predictable JSON files in a temporary settings directory, which can be accessed by attackers with read permissions to recover the keys.

Useful 0 Not Useful 0

Detection Guidance

Check for timestamp-based JSON files in the ./tmp/webui_settings/ directory. Look for files matching the pattern YYYYMMDD-HHMMSS.json. Use commands like 'find / -type f -name "*.json" -path "*/webui_settings/*"' to locate them. Verify file permissions with 'ls -la' to confirm they are world-readable (mode 644).

Inspect Gradio API endpoints for unauthenticated /save_config access. Use network scanning tools like 'nmap' to check for open ports and endpoints. Monitor logs for suspicious API calls to /save_config.

Useful 0 Not Useful 0

Impact Analysis

Attackers with access to the settings directory can extract LLM API keys, leading to unauthorized use of paid services, data breaches, or further attacks. In shared environments like Docker deployments with bind mounts, even non-privileged users may access these keys.

Useful 0 Not Useful 0

Compliance Impact

This vulnerability likely violates compliance requirements for protecting sensitive data like API keys. GDPR and HIPAA mandate encryption and access controls for personal and health information, which may extend to credentials used in processing such data.

Useful 0 Not Useful 0

Mitigation Strategies

Upgrade browser-use web-ui to a version beyond 3.0.0 where the issue is fixed. If upgrading is not possible, restrict access to the ./tmp/webui_settings/ directory using file permissions (chmod 700).

Implement authentication for the Gradio API endpoint /save_config. Disable world-readable permissions on configuration files. Rotate all exposed LLM API keys immediately.

Useful 0 Not Useful 0