CVE-2021-38290
📋 TL;DR
This CVE describes a host header injection vulnerability in FUEL CMS versions 1.5.0 through fuel/modules/fuel/config/fuel_constants.php and fuel/modules/fuel/libraries/Asset.php. Attackers can exploit this via man-in-the-middle attacks like phishing to manipulate host headers, potentially leading to cache poisoning, password reset poisoning, or cross-site scripting. Organizations running vulnerable FUEL CMS installations are affected.
💻 Affected Systems
- FUEL CMS
📦 What is this software?
Fuel Cms by Thedaylightstudio
⚠️ Risk & Real-World Impact
Worst Case
Successful exploitation could allow attackers to perform cache poisoning attacks, redirect users to malicious sites, steal session cookies via XSS, or manipulate password reset functionality to compromise user accounts.
Likely Case
Attackers would most likely use this vulnerability for phishing campaigns by redirecting users to malicious websites that appear legitimate, potentially leading to credential theft or malware installation.
If Mitigated
With proper input validation and host header verification in place, the attack surface is significantly reduced, though some risk remains if the underlying vulnerability isn't patched.
🎯 Exploit Status
The vulnerability is relatively easy to exploit as it doesn't require authentication and host header manipulation is a well-known attack vector with available tools.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Patched in commit 8a0d88ad6869623c90e24b3b2ea33352049d39a7
Vendor Advisory: https://github.com/daylightstudio/FUEL-CMS/commit/8a0d88ad6869623c90e24b3b2ea33352049d39a7
Restart Required: No
Instructions:
1. Update to the latest FUEL CMS version. 2. Apply the specific patch from commit 8a0d88ad6869623c90e24b3b2ea33352049d39a7. 3. Replace affected files: fuel/modules/fuel/config/fuel_constants.php and fuel/modules/fuel/libraries/Asset.php with patched versions.
🔧 Temporary Workarounds
Host Header Validation
allImplement server-side validation of host headers to only accept expected domain names
Web Server Configuration
allConfigure web server (Apache/Nginx) to validate and sanitize host headers
🧯 If You Can't Patch
- Implement WAF rules to detect and block suspicious host header manipulation
- Monitor logs for unusual host header patterns and implement alerting
🔍 How to Verify
Check if Vulnerable:
Check if your FUEL CMS installation contains the vulnerable files: fuel/modules/fuel/config/fuel_constants.php and fuel/modules/fuel/libraries/Asset.php from versions 1.5.0 onwardCheck Version:
Check FUEL CMS version in configuration files or via admin interfaceVerify Fix Applied:
Verify that the patched files from commit 8a0d88ad6869623c90e24b3b2ea33352049d39a7 are present and compare checksums📡 Detection & Monitoring
Log Indicators:
- Unusual host header values in web server logs
- Multiple requests with varying host headers from same source
- Requests with host headers containing suspicious characters or domains
Network Indicators:
- HTTP requests with manipulated host headers
- Traffic patterns suggesting host header injection attempts
SIEM Query:
source="web_server_logs" AND (host_header CONTAINS "malicious-domain.com" OR host_header MATCHES "[^a-zA-Z0-9.-]")