CVE-2025-55271: HCLTech Aftermarket Cloud RCE Vulnerability

CVE-2025-55271 Overview

HCL Aftermarket DPC is affected by an HTTP Response Splitting vulnerability that allows attackers to manipulate HTTP responses by injecting malicious content into response headers. Depending on how the web application handles the split response, an attacker may be able to execute arbitrary commands or inject harmful content into the response, potentially leading to cross-site scripting attacks, cache poisoning, or session hijacking.

Critical Impact

This vulnerability enables attackers to inject malicious content into HTTP responses, potentially compromising user sessions, enabling XSS attacks, and poisoning web caches affecting multiple users.

Affected Products

• HCL Aftermarket Cloud 1.0.0

Discovery Timeline

• 2026-03-26 - CVE CVE-2025-55271 published to NVD
• 2026-03-26 - Last updated in NVD database

Technical Details for CVE-2025-55271

Vulnerability Analysis

This HTTP Response Splitting vulnerability (CWE-113) occurs when user-controlled input is improperly sanitized before being included in HTTP response headers. The vulnerability allows attackers to inject carriage return (CR) and line feed (LF) characters into header values, effectively splitting the HTTP response into multiple responses.

When exploited, the attacker can control the content of subsequent responses, enabling various attack scenarios including cross-site scripting, web cache poisoning, and browser cache poisoning. The network-based attack vector means the vulnerability can be exploited remotely, though user interaction is required for successful exploitation.

Root Cause

The root cause lies in improper neutralization of CRLF sequences in HTTP headers. The application fails to properly validate and sanitize user input before incorporating it into HTTP response headers. When special characters like \r\n (CRLF) are not filtered, attackers can terminate the current header and inject arbitrary headers or even a complete new HTTP response body.

Attack Vector

The attack exploits the network-accessible nature of the HCL Aftermarket DPC application. An attacker crafts malicious input containing CRLF sequences that, when processed by the vulnerable application, splits the HTTP response. This can be achieved through URL parameters, form inputs, or any user-controllable data that gets reflected in HTTP response headers.

A typical attack flow involves:

1. The attacker identifies a parameter that gets reflected in response headers
2. The attacker injects CRLF sequences followed by malicious headers or body content
3. The server fails to sanitize the input and includes it in the response
4. The victim's browser interprets the split response, executing the attacker's payload

For detailed technical information, refer to the HCL Software Knowledge Base Article.

Detection Methods for CVE-2025-55271

Indicators of Compromise

• HTTP requests containing encoded or raw CRLF sequences (%0d%0a, \r\n) in parameter values
• Unusual patterns in web server access logs showing header injection attempts
• Application logs indicating malformed or unexpected header values
• Evidence of cache poisoning with unexpected content served from cache

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect and block CRLF injection patterns in request parameters
• Implement input validation monitoring to alert on CRLF sequences in user-supplied data
• Review HTTP response headers for anomalies or unexpected content injections
• Monitor for cache poisoning indicators by comparing cached responses against expected content

Monitoring Recommendations

• Enable detailed logging for all HTTP requests and responses in HCL Aftermarket Cloud
• Configure alerts for requests containing common HTTP Response Splitting payloads
• Monitor web cache hit rates and content integrity for signs of poisoning
• Implement continuous security scanning to detect exploitation attempts

How to Mitigate CVE-2025-55271

Immediate Actions Required

• Review and apply the vendor-provided patch from HCL Software immediately
• Implement input validation to reject any user input containing CR or LF characters
• Deploy WAF rules to block HTTP Response Splitting attack patterns
• Audit application code for instances where user input is reflected in HTTP headers

Patch Information

HCL Software has released a security advisory and patch for this vulnerability. Administrators should consult the HCL Software Knowledge Base Article for detailed patching instructions and download the latest security update for HCL Aftermarket Cloud.

Workarounds

• Implement strict input validation that strips or encodes CR and LF characters from all user input
• Use a reverse proxy or WAF to filter CRLF injection attempts before they reach the application
• Disable or restrict features that reflect user input in HTTP headers until patching is complete
• Implement Content-Security-Policy headers to mitigate potential XSS impacts from successful exploitation

# Example WAF rule to block CRLF injection attempts (ModSecurity)
SecRule ARGS "@rx (%0d|%0a|\\r|\\n)" \
    "id:1001,phase:1,deny,status:403,msg:'HTTP Response Splitting attempt detected'"