CVE-2023-34053: VMware Spring Framework DoS Vulnerability

CVE-2023-34053 Overview

A Denial of Service (DoS) vulnerability exists in Spring Framework versions 6.0.0 through 6.0.13 that allows attackers to cause service disruption through specially crafted HTTP requests. This vulnerability affects applications using Spring MVC or Spring WebFlux when combined with Micrometer observation capabilities.

Critical Impact

Attackers can exploit this vulnerability to cause denial-of-service conditions in affected Spring Framework applications, potentially disrupting critical business services and web applications.

Affected Products

• VMware Spring Framework versions 6.0.0 - 6.0.13
• Spring Boot applications with spring-boot-actuator dependency
• Applications using Spring MVC or Spring WebFlux with Micrometer observation enabled

Discovery Timeline

• November 28, 2023 - CVE CVE-2023-34053 published to NVD
• February 13, 2025 - Last updated in NVD database

Technical Details for CVE-2023-34053

Vulnerability Analysis

This vulnerability enables remote attackers to trigger a denial-of-service condition through maliciously crafted HTTP requests. The attack does not require authentication and can be executed remotely over the network with low complexity.

The vulnerability specifically manifests when three conditions are met simultaneously: the application utilizes Spring MVC or Spring WebFlux, the io.micrometer:micrometer-core library is present on the classpath, and an ObservationRegistry is configured to record observations. Spring Boot applications are particularly susceptible when they include the org.springframework.boot:spring-boot-actuator dependency, as this configuration commonly satisfies all required conditions.

Root Cause

The root cause of this vulnerability stems from improper handling of HTTP request processing in Spring Framework's observation recording mechanism. When Micrometer observation is enabled, the framework fails to properly validate or limit certain aspects of incoming HTTP requests, allowing attackers to craft requests that consume excessive server resources.

Attack Vector

The attack is network-based and requires no user interaction or authentication. An attacker can remotely send specially crafted HTTP requests to vulnerable applications. The requests exploit the observation recording mechanism, causing the application to enter a state where it cannot process legitimate requests, effectively denying service to authorized users.

The vulnerability is particularly concerning for internet-facing Spring Boot applications with actuator endpoints enabled, as these commonly meet all the prerequisite conditions for exploitation.

Detection Methods for CVE-2023-34053

Indicators of Compromise

• Unusual spikes in HTTP request volume from single or multiple source IP addresses
• Application performance degradation or unresponsiveness correlated with specific request patterns
• Increased memory or CPU utilization on application servers without corresponding legitimate traffic increases
• Log entries indicating abnormal request processing times or timeout errors

Detection Strategies

• Implement application performance monitoring (APM) to detect anomalous response times and throughput degradation
• Configure Web Application Firewall (WAF) rules to identify and block malformed or suspicious HTTP request patterns
• Deploy network intrusion detection systems (NIDS) with signatures targeting DoS attack patterns against Spring Framework applications
• Monitor JVM metrics for unusual memory allocation patterns or garbage collection anomalies

Monitoring Recommendations

• Enable detailed request logging in Spring Boot applications to capture request characteristics for forensic analysis
• Configure alerting thresholds for application availability and response time metrics
• Implement rate limiting at the load balancer or API gateway level to mitigate volumetric attacks
• Monitor Spring Boot Actuator health endpoints for degraded application status

How to Mitigate CVE-2023-34053

Immediate Actions Required

• Upgrade Spring Framework to version 6.0.14 or later to apply the security patch
• Review application dependencies to identify presence of io.micrometer:micrometer-core and spring-boot-actuator
• Implement network-level rate limiting to reduce exposure while patches are applied
• Consider temporarily disabling observation recording if the feature is not critical for production monitoring

Patch Information

VMware has released patches to address this vulnerability. Organizations should upgrade to Spring Framework 6.0.14 or later. For detailed patch information and upgrade guidance, refer to the Spring Security Advisory for CVE-2023-34053. Additional vendor advisories are available from NetApp Security Advisory NTAP-20231214-0007.

Workarounds

• Disable Micrometer observation by removing the ObservationRegistry bean configuration if observation features are not required
• Remove the io.micrometer:micrometer-core dependency from the classpath if not essential for application functionality
• Implement strict input validation at the application gateway level to filter potentially malicious requests
• Deploy a reverse proxy with request filtering capabilities to sanitize incoming HTTP traffic before it reaches the application

# Example: Check Spring Framework version in Maven project
mvn dependency:tree | grep spring-framework

# Example: Check for affected dependencies
mvn dependency:tree | grep -E "(micrometer-core|spring-boot-actuator)"

# Upgrade Spring Framework in pom.xml to patched version
# Update version to 6.0.14 or later