CVE-2016-5325 in Node.js
Summary
by MITRE
CRLF injection vulnerability in the ServerResponse#writeHead function in Node.js 0.10.x before 0.10.47, 0.12.x before 0.12.16, 4.x before 4.6.0, and 6.x before 6.7.0 allows remote attackers to inject arbitrary HTTP headers and conduct HTTP response splitting attacks via the reason argument.
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Analysis
by VulDB Data Team • 09/22/2022
The CVE-2016-5325 vulnerability represents a critical CRLF injection flaw in Node.js server response handling mechanisms that fundamentally compromises HTTP header integrity. This vulnerability exists within the ServerResponse#writeHead function across multiple Node.js versions, creating a pathway for attackers to manipulate HTTP responses through carefully crafted input. The flaw specifically targets the reason argument parameter, which is used to set the HTTP status message in response headers, allowing malicious actors to inject carriage return and line feed characters that can alter the response structure.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization of the reason argument parameter within the writeHead function. When Node.js processes HTTP responses, it directly incorporates user-supplied reason text into the response headers without proper escaping or validation of CRLF sequences. Attackers can exploit this by injecting characters such as \r (carriage return) and \n (line feed) followed by additional HTTP headers, effectively splitting the original response into multiple responses. This creates a condition where an attacker can inject malicious headers, redirect responses, or manipulate browser behavior through HTTP response splitting techniques.
The operational impact of CVE-2016-5325 extends beyond simple header injection, as it enables sophisticated attack vectors including cache poisoning, cross-site scripting exploitation, and session hijacking. When combined with other vulnerabilities or used in conjunction with web application attacks, this flaw can facilitate more severe security breaches. The vulnerability affects a wide range of Node.js versions, making it particularly dangerous as many applications were running these outdated versions when the vulnerability was discovered. The attack surface includes any Node.js application that accepts user input for HTTP status messages or uses dynamic reason arguments in their response handling code.
This vulnerability aligns with CWE-113, which addresses improper neutralization of CRLF characters in HTTP headers, and maps to ATT&CK technique T1071.004 for application layer protocol manipulation. Organizations running affected Node.js versions face significant risk of unauthorized header injection that can lead to complete session compromise or data exfiltration. The vulnerability demonstrates a classic input validation failure that requires proper sanitization of all user-supplied data before incorporation into HTTP headers. Security teams should prioritize immediate patching of affected systems and implement input validation measures to prevent similar vulnerabilities in custom application code that handles HTTP responses.
Mitigation strategies include immediate upgrade to patched Node.js versions, implementation of strict input validation for all HTTP header parameters, and deployment of web application firewalls that can detect and block CRLF injection attempts. Organizations should also conduct comprehensive code reviews to identify any custom implementations that might be vulnerable to similar injection flaws, particularly in areas where user input is directly used in HTTP response construction. The vulnerability underscores the importance of secure coding practices and proper input sanitization in server-side applications, particularly those handling user-facing HTTP responses.