CVE-2023-20873: Spring Boot Auth Bypass Vulnerability

CVE-2023-20873 Overview

CVE-2023-20873 is a security bypass vulnerability affecting Spring Boot applications deployed to Cloud Foundry environments. The vulnerability allows attackers to bypass security controls, potentially leading to unauthorized access to application resources and sensitive data. This flaw impacts Spring Boot versions 3.0.0 through 3.0.5, versions 2.7.0 through 2.7.10, and older unsupported versions.

Critical Impact

Applications deployed to Cloud Foundry could be susceptible to a complete security bypass, allowing unauthenticated attackers to gain unauthorized access with potential for data compromise.

Affected Products

• VMware Spring Boot versions 3.0.0 - 3.0.5
• VMware Spring Boot versions 2.7.0 - 2.7.10
• Older unsupported versions of VMware Spring Boot

Discovery Timeline

• April 20, 2023 - CVE-2023-20873 published to NVD
• May 5, 2025 - Last updated in NVD database

Technical Details for CVE-2023-20873

Vulnerability Analysis

This security bypass vulnerability affects Spring Boot applications specifically when deployed to Cloud Foundry environments. The flaw enables attackers to circumvent authentication and authorization mechanisms that would normally protect application endpoints and resources.

The vulnerability requires no authentication or user interaction to exploit, making it particularly dangerous for internet-facing applications. Successful exploitation could result in complete compromise of confidentiality, integrity, and availability of the affected application and its data.

Root Cause

The root cause stems from improper security constraint handling within Spring Boot when applications are deployed to Cloud Foundry infrastructure. The platform-specific deployment context introduces a security bypass condition that is not present in other deployment scenarios. This indicates an issue with how Spring Boot integrates with Cloud Foundry's security model, allowing certain requests to bypass intended security checks.

Attack Vector

The attack vector is network-based, requiring no privileges or user interaction. An attacker can remotely exploit this vulnerability by sending specially crafted requests to a vulnerable Spring Boot application deployed on Cloud Foundry. The low attack complexity combined with the network accessibility makes this vulnerability particularly exploitable.

The exploitation mechanism involves leveraging the security bypass condition to access protected resources or functionality that should be restricted. Without proper security constraints in place, attackers can potentially access administrative endpoints, sensitive data, or execute privileged operations.

Detection Methods for CVE-2023-20873

Indicators of Compromise

• Unusual access patterns to Spring Boot actuator endpoints from unauthorized sources
• Authentication bypass attempts in application logs showing successful access without valid credentials
• Unexpected requests to sensitive endpoints from external IP addresses
• Anomalous traffic patterns targeting Cloud Foundry-deployed Spring Boot applications

Detection Strategies

• Monitor application access logs for successful requests to protected endpoints without corresponding authentication events
• Implement network traffic analysis to detect requests attempting to bypass security controls
• Deploy web application firewall (WAF) rules to detect and block exploitation attempts
• Configure alerting for access to sensitive actuator or management endpoints from untrusted sources

Monitoring Recommendations

• Enable verbose logging for Spring Security to capture authentication and authorization decisions
• Monitor Cloud Foundry audit logs for suspicious application access patterns
• Implement real-time alerting for unexpected access to administrative endpoints
• Review and audit application access logs regularly for signs of security bypass attempts

How to Mitigate CVE-2023-20873

Immediate Actions Required

• Upgrade Spring Boot 3.0.x applications to version 3.0.6 or later immediately
• Upgrade Spring Boot 2.7.x applications to version 2.7.11 or later immediately
• Migrate applications running on older unsupported versions to 3.0.6+ or 2.7.11+
• Review application logs for any signs of past exploitation attempts

Patch Information

VMware has released patched versions of Spring Boot that address this vulnerability. Users should upgrade to the following versions:

• Spring Boot 3.0.x: Upgrade to version 3.0.6 or later
• Spring Boot 2.7.x: Upgrade to version 2.7.11 or later

For detailed patch information, refer to the Spring Security Advisory for CVE-2023-20873. Additional information is available in the Spring Blog Update for Boot Versions and the NetApp Security Advisory NTAP-20230601-0009.

Workarounds

• Implement additional authentication layers at the Cloud Foundry platform level while awaiting patch deployment
• Restrict network access to Cloud Foundry-deployed applications using platform security groups
• Enable and configure Spring Security with explicit security constraints for all endpoints
• Consider temporarily restricting access to sensitive actuator endpoints until patches are applied

# Example: Restrict actuator endpoints in application.properties
management.endpoints.web.exposure.include=health,info
management.endpoint.health.show-details=never
management.endpoints.web.base-path=/internal/actuator