CVE-2025-55763
📋 TL;DR
A buffer overflow vulnerability in CivetWeb's URI parser allows remote attackers to execute arbitrary code via specially crafted HTTP requests. This affects all CivetWeb versions 1.14 through 1.16 when exposed to untrusted network traffic. Attackers can exploit this to take control of affected servers or cause denial of service.
💻 Affected Systems
- CivetWeb embedded web server
📦 What is this software?
Civetweb by Civetweb Project
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, and persistent backdoor installation.
Likely Case
Denial of service through application crashes or limited remote code execution in constrained environments.
If Mitigated
Limited impact if proper network segmentation and input validation controls are implemented.
🎯 Exploit Status
Public proof-of-concept available on GitHub; exploitation requires sending crafted HTTP requests.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Not yet released
Vendor Advisory: https://github.com/civetweb/civetweb
Restart Required: Yes
Instructions:
1. Monitor CivetWeb GitHub repository for security updates. 2. Apply patch when available. 3. Restart affected services.
🔧 Temporary Workarounds
Network Segmentation
linuxRestrict access to CivetWeb services to trusted networks only
iptables -A INPUT -p tcp --dport 8080 -s trusted_network -j ACCEPT
iptables -A INPUT -p tcp --dport 8080 -j DROP
Reverse Proxy with Input Validation
allPlace CivetWeb behind a reverse proxy that validates and sanitizes HTTP requests
🧯 If You Can't Patch
- Implement strict network access controls to limit exposure
- Deploy web application firewall with buffer overflow protection rules
🔍 How to Verify
Check if Vulnerable:
Check CivetWeb version: grep -i version /path/to/civetweb/binary or check application logsCheck Version:
strings /path/to/civetweb | grep -i versionVerify Fix Applied:
Verify version is updated beyond 1.16 after patch release📡 Detection & Monitoring
Log Indicators:
- Unusual long URI requests
- Application crashes with memory corruption errors
- Malformed HTTP request patterns
Network Indicators:
- HTTP requests with abnormally long URIs
- Requests containing non-standard URI characters
- Rapid sequence of malformed requests
SIEM Query:
source="web_logs" AND (uri_length>2048 OR uri CONTAINS "%00" OR uri CONTAINS "..")