CVE-2024-4027
📋 TL;DR
This vulnerability in Undertow allows remote attackers to cause denial-of-service by sending HTTP requests with large parameter names, triggering OutOfMemoryError. It affects applications using servlets that call HttpServletRequestImpl.getParameterNames(). Unauthorized users can exploit this to crash vulnerable servers.
💻 Affected Systems
- Undertow
- Red Hat JBoss EAP
- Red Hat JBoss Web Server
- Applications using Undertow servlet container
⚠️ Manual Verification Required
This CVE does not have specific version information in our database, so automatic vulnerability detection cannot determine if your system is affected.
Why? The CVE database entry doesn't specify which versions are vulnerable (no version ranges provided by the vendor/NVD).
🔒 Custom verification scripts are available for registered users. Sign up free to download automated test scripts.
- Review the CVE details at NVD
- Check vendor security advisories for your specific version
- Test if the vulnerability is exploitable in your environment
- Consider updating to the latest version as a precaution
⚠️ Risk & Real-World Impact
Worst Case
Complete service unavailability due to memory exhaustion, requiring server restart and potentially causing extended downtime.
Likely Case
Intermittent service disruptions and performance degradation as servers struggle with memory pressure from malicious requests.
If Mitigated
Minimal impact with proper monitoring, rate limiting, and memory constraints in place to detect and block malicious traffic.
🎯 Exploit Status
Simple HTTP request crafting required. No authentication needed. Attack tools could easily incorporate this exploit.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Undertow 2.3.14.Final and later
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2024-4027
Restart Required: Yes
Instructions:
1. Update Undertow to version 2.3.14.Final or later. 2. Update dependent applications (JBoss EAP, JBoss Web Server) to patched versions. 3. Restart application servers. 4. Test applications for compatibility.
🔧 Temporary Workarounds
Request size limiting
allConfigure maximum HTTP request size to limit parameter name lengths
In Undertow configuration: max-entity-size=1048576
max-parameters=1000
Web Application Firewall rules
allBlock requests with unusually long parameter names
WAF rule: Block HTTP requests with parameter names > 1024 characters
🧯 If You Can't Patch
- Implement rate limiting and request filtering at network perimeter
- Monitor memory usage and restart services when thresholds exceeded
🔍 How to Verify
Check if Vulnerable:
Check Undertow version: java -jar undertow-core.jar --version or examine application server versionCheck Version:
java -cp "undertow-core.jar" io.undertow.VersionVerify Fix Applied:
Confirm Undertow version is 2.3.14.Final or later. Test with crafted requests containing large parameter names.📡 Detection & Monitoring
Log Indicators:
- OutOfMemoryError in application logs
- High memory usage alerts
- Repeated requests with large parameter names
Network Indicators:
- HTTP requests with abnormally long parameter names (>1KB)
- Spike in request size
SIEM Query:
source="app.log" AND "OutOfMemoryError" AND "HttpServletRequestImpl.getParameterNames"