Directory Traversal with spring-cloud-config-server
Description
Spring Cloud Config Server versions 2.2.x prior to 2.2.3, versions 2.1.x prior to 2.1.9, and older unsupported versions contain a directory traversal vulnerability (CVE-2020-5410). The vulnerability exists in the spring-cloud-config-server module, which fails to properly validate user-supplied input in configuration file requests. Attackers can exploit this flaw by crafting malicious URLs with path traversal sequences (e.g., ../) to access arbitrary files on the server's filesystem outside the intended configuration directory.
Remediation
Apply the following remediation steps immediately:
1. Upgrade to a patched version:
- For 2.2.x branch: Upgrade to version 2.2.3 or later
- For 2.1.x branch: Upgrade to version 2.1.9 or later
- For older unsupported versions: Migrate to a currently supported and patched version
2. Network segmentation:
- Ensure spring-cloud-config-server is only accessible from trusted internal networks
- Implement firewall rules to block external access to the configuration server
- Use VPN or other secure access methods for remote administration
3. Additional security measures:
- Enable authentication and authorization for all configuration server endpoints
- Implement request logging and monitoring to detect potential exploitation attempts
- Conduct a security audit to verify no unauthorized file access has occurred prior to patching