CVE-2025-50578
📋 TL;DR
CVE-2025-50578 allows unauthenticated attackers to manipulate HTTP headers (X-Forwarded-Host and Referer) to perform Host Header Injection and Open Redirect attacks. This enables loading external resources from attacker-controlled domains and redirecting users to malicious sites, potentially leading to phishing, UI redress, and session theft. All Heimdall 2.6.3-ls307 instances are affected.
💻 Affected Systems
- LinuxServer.io Heimdall
📦 What is this software?
Docker Heimdall by Linuxserver
⚠️ Risk & Real-World Impact
Worst Case
Attackers redirect users to phishing sites that steal credentials, perform session hijacking, and load malicious content that compromises user systems.
Likely Case
Phishing attacks via open redirects leading to credential theft and potential session compromise.
If Mitigated
Limited impact with proper input validation and header sanitization in place.
🎯 Exploit Status
Exploitation requires only HTTP header manipulation with no authentication.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check GitHub for latest patched version
Vendor Advisory: https://github.com/linuxserver/Heimdall/issues/1451
Restart Required: Yes
Instructions:
1. Update Heimdall to latest version
2. Restart Heimdall service
3. Verify headers are properly validated
🔧 Temporary Workarounds
Web Server Header Filtering
linuxConfigure reverse proxy or web server to strip or validate X-Forwarded-Host and Referer headers
# Example nginx config: proxy_set_header X-Forwarded-Host $host;
# Apache: RequestHeader unset X-Forwarded-Host
🧯 If You Can't Patch
- Implement WAF rules to block malicious header patterns
- Monitor for suspicious redirect patterns in logs
🔍 How to Verify
Check if Vulnerable:
Test by sending HTTP requests with manipulated X-Forwarded-Host or Referer headers and observing redirect behaviorCheck Version:
docker inspect heimdall | grep versionVerify Fix Applied:
Test header manipulation attempts after patch - should reject or sanitize malicious headers📡 Detection & Monitoring
Log Indicators:
- Unusual Referer headers
- Multiple redirects to external domains
- X-Forwarded-Host header mismatches
Network Indicators:
- HTTP 302 redirects to unexpected domains
- Header manipulation patterns in requests
SIEM Query:
source="heimdall" AND (http_referer="*malicious*" OR http_x_forwarded_host="*malicious*")