CVE-2023-20873 - Security Bypass Vulnerability in Spring Boot on Cloud Foundry

Overview

CVE-2023-20873 is a security bypass vulnerability affecting Spring Boot applications deployed on Cloud Foundry platforms. The vulnerability exists in Spring Boot versions 3.. to 3..5, 2.7. to 2.7.10, and older unsupported versions. This post will detail the exploit, provide code snippets, and link to original references to help users understand the issue and apply mitigations.

Exploit Details

The vulnerability allows unauthorized access to sensitive data and resources of Spring Boot applications deployed on Cloud Foundry. An attacker can exploit this vulnerability by bypassing authentication and authorization checks. This could lead to unauthorized actions like data manipulation, exfiltration, or system compromise.

To demonstrate the security bypass, consider the following example

@SpringBootApplication
public class DemoApplication {    
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }
    
    @RestController
    public class DemoController {
        @GetMapping("/secured")
        @Secured({"ROLE_USER"})
        public String secured() {
            return "Access granted to ROLE_USER";
        }
    }
}

The code defines a simple Spring Boot application and a /secured endpoint secured using @Secured annotation with the ROLE_USER role. The security bypass vulnerability allows an unauthenticated attacker to access this endpoint without valid credentials.

Users of older, unsupported versions should upgrade to 3..6 or later or 2.7.11 or later

Upgrading the Spring Boot version can be done by updating your project's build configuration (e.g., pom.xml for Maven or build.gradle for Gradle) and setting the new desired Spring Boot version.

Original References

- CVE details: CVE-2023-20873
- Spring security advisory: Spring Boot and Cloud Foundry Integration
- Release notes for fixed versions: Spring Boot 3..6 Release Notes, Spring Boot 2.7.11 Release Notes

Conclusion

CVE-2023-20873 is a critical security bypass vulnerability affecting Spring Boot applications deployed on Cloud Foundry. Users of the affected versions are urged to upgrade to versions 3..6+, 2.7.11+, or other unaffected versions to resolve the issue. Following the mitigation steps and staying informed about security advisories will help maintain strong security practices for your Spring Boot applications.

Timeline

Published on: 04/20/2023 21:15:00 UTC
Last modified on: 06/01/2023 14:15:00 UTC