Check in seconds if your cPanel/WHM installation allows CRLF (Carriage Return Line Feed) injection at the /login/?user= endpoint. Non-destructive test, instant result, remediation plan included.
/login/?user=Everything you need to know about this injection and how to protect your server
Allows an attacker to inject carriage return and line feed characters (\r\n) into HTTP headers. Enables response manipulation, session hijacking, cache poisoning and reflected XSS.
The user parameter in the /login/ endpoint does not properly filter encoded %0D%0A characters, allowing an attacker to introduce arbitrary HTTP headers in the server response.
Update cPanel/WHM to the latest version immediately. Implement a WAF with control character filtering, configure strict security headers and monitor server logs regularly.
Answers to common questions about CRLF injection, detection and remediation
%0D%0A characters in HTTP parameters, mainly in the /login/?user= endpoint. This enables response header manipulation, reflected XSS attacks, web cache poisoning, and administrative session hijacking. Also known as HTTP Response Splitting.X-Vulnerable-Test:YES. If the server reflects it in its HTTP response, it is vulnerable to CRLF injection and must be patched immediately./usr/local/cpanel/cpanel -V from SSH and consult the official cPanel changelog to confirm if your build includes the CRLF injection fix. LTS tier builds without updates are most exposed./scripts/upcp --force from SSH as root. As temporary mitigation, you can add ModSecurity rules that block %0D%0A sequences in URIs and arguments. This tool automatically generates a complete remediation plan with copyable commands when it detects vulnerability.2087 (SSL) or 2086 (non-SSL), while cPanel uses 2083 (SSL) or 2082 (non-SSL). Enter the URL including the port, for example https://your-server.com:2087. The CRLF test applies to the underlying login module (cpsrvd) shared by cPanel and WHM./usr/local/apache/logs/access_log), like any normal HTTP request. This is expected in a legitimate audit.Audit, urgent patching and professional hardening by a sysadmin with 12+ years of experience in cPanel/WHM, server security and VoIP infrastructure. Free quote in less than 24 hours, no commitments.
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This tool is designed exclusively for system administrators to verify their own servers or those they have explicit authorization for. Unauthorized use against third-party systems may constitute a crime under laws such as the Computer Fraud and Abuse Act (CFAA) in the US, the Budapest Convention on cybercrime or local equivalents. The test performed is non-destructive: it only verifies the reflection of an innocuous test header and does not compromise the system. You are fully responsible for the use you give to this tool.