CVE-2024-3884
📋 TL;DR
This vulnerability in Undertow allows remote attackers to cause denial of service by sending specially crafted large form data with application/x-www-form-urlencoded encoding, triggering an OutOfMemory error. Any system running vulnerable versions of Undertow that processes form data is affected. The attack requires no authentication.
💻 Affected Systems
- Undertow
⚠️ 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, potentially affecting all applications on the server.
Likely Case
Service disruption and performance degradation as the server struggles with memory allocation.
If Mitigated
Limited impact with proper memory limits and monitoring in place.
🎯 Exploit Status
Attack requires sending large form data payloads but no special tools needed.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check Red Hat advisories RHSA-2026:0383, RHSA-2026:0384, RHSA-2026:0386 for specific patched versions.
Vendor Advisory: https://access.redhat.com/security/cve/CVE-2024-3884
Restart Required: Yes
Instructions:
1. Review Red Hat advisories for your specific Undertow version. 2. Apply the recommended patch or update to a fixed version. 3. Restart the Undertow service or application server.
🔧 Temporary Workarounds
Limit form data size
allConfigure maximum allowed size for form data to prevent large payloads from being processed.
Configure max-post-size parameter in Undertow configuration
Implement request filtering
allUse web application firewall or reverse proxy to filter large form data requests.
Configure WAF rules to block large application/x-www-form-urlencoded requests
🧯 If You Can't Patch
- Implement strict input validation and size limits on form data processing
- Deploy monitoring for memory usage spikes and implement automatic restart policies
🔍 How to Verify
Check if Vulnerable:
Check Undertow version against Red Hat advisories; examine if application processes form data with vulnerable method.Check Version:
Check application server logs or configuration files for Undertow version informationVerify Fix Applied:
Verify Undertow version is updated to patched version listed in Red Hat advisories.📡 Detection & Monitoring
Log Indicators:
- OutOfMemoryError in logs
- High memory usage alerts
- Failed form parsing requests
Network Indicators:
- Large POST requests with application/x-www-form-urlencoded content-type
SIEM Query:
source="undertow.log" AND ("OutOfMemory" OR "java.lang.OutOfMemoryError")🔗 References
- https://access.redhat.com/errata/RHSA-2026:0383
- https://access.redhat.com/errata/RHSA-2026:0384
- https://access.redhat.com/errata/RHSA-2026:0386
- https://access.redhat.com/errata/RHSA-2026:3889
- https://access.redhat.com/errata/RHSA-2026:3891
- https://access.redhat.com/errata/RHSA-2026:3892
- https://access.redhat.com/security/cve/CVE-2024-3884
- https://bugzilla.redhat.com/show_bug.cgi?id=2275287
