CVE-2023-20883
📋 TL;DR
This vulnerability in Spring Boot allows denial-of-service attacks when Spring MVC applications are deployed behind reverse proxy caches. Attackers can send specially crafted requests that cause the application to consume excessive resources, potentially making it unavailable. Affected systems include Spring Boot applications using Spring MVC with reverse proxy caching in vulnerable versions.
💻 Affected Systems
- Spring Boot
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete application unavailability due to resource exhaustion, affecting all users and potentially causing business disruption.
Likely Case
Degraded application performance or intermittent outages affecting user experience.
If Mitigated
Minimal impact with proper rate limiting, monitoring, and updated versions.
🎯 Exploit Status
Attack requires knowledge of application endpoints and reverse proxy configuration.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Spring Boot 3.0.7+, 2.7.12+, 2.6.15+, 2.5.15+
Vendor Advisory: https://spring.io/security/cve-2023-20883
Restart Required: Yes
Instructions:
1. Update Spring Boot dependencies to patched versions. 2. Rebuild and redeploy application. 3. Verify version update.
🔧 Temporary Workarounds
Disable reverse proxy caching
allConfigure reverse proxy to not cache responses from Spring MVC endpoints
# Configure nginx: proxy_cache off;
# Configure Apache: CacheDisable /
Implement rate limiting
allAdd rate limiting at reverse proxy or application level to prevent DoS
# nginx: limit_req_zone, limit_req
# Spring Security: configure rate limiting
🧯 If You Can't Patch
- Implement strict rate limiting and request validation
- Monitor application resource usage and set up alerts for abnormal patterns
🔍 How to Verify
Check if Vulnerable:
Check Spring Boot version in pom.xml or build.gradle and verify if using Spring MVC with reverse proxy cacheCheck Version:
java -jar your-app.jar --version or check build configuration filesVerify Fix Applied:
Verify Spring Boot version is updated to patched version and test application functionality📡 Detection & Monitoring
Log Indicators:
- High frequency of similar requests
- Increased error rates
- Resource exhaustion warnings
Network Indicators:
- Unusual request patterns to MVC endpoints
- High traffic volume from single sources
SIEM Query:
source="application.logs" AND ("resource exhaustion" OR "high request rate")