CVE-2016-2216 in Xcode
Summary
by MITRE
The HTTP header parsing code in Node.js 0.10.x before 0.10.42, 0.11.6 through 0.11.16, 0.12.x before 0.12.10, 4.x before 4.3.0, and 5.x before 5.6.0 allows remote attackers to bypass an HTTP response-splitting protection mechanism via UTF-8 encoded Unicode characters in the HTTP header, as demonstrated by %c4%8d%c4%8a.
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Analysis
by VulDB Data Team • 09/28/2022
The vulnerability described in CVE-2016-2216 represents a critical security flaw in Node.js HTTP header parsing mechanisms that affects multiple versions of the JavaScript runtime environment. This vulnerability specifically targets the way Node.js processes HTTP headers containing UTF-8 encoded Unicode characters, creating a pathway for attackers to circumvent built-in security protections designed to prevent HTTP response splitting attacks. The flaw exists in the parsing logic that handles character encoding in HTTP headers, allowing malicious actors to inject control characters that are normally blocked by security mechanisms. The vulnerability is particularly concerning because it affects widely used Node.js versions across different release branches, including the long-term support 0.10.x series and newer 4.x and 5.x releases, making it a significant concern for organizations maintaining legacy systems.
The technical implementation of this vulnerability stems from improper handling of UTF-8 encoded characters within HTTP header values during the parsing process. When Node.js encounters HTTP headers containing specific UTF-8 byte sequences such as %c4%8d%c4%8a, the parsing code fails to properly sanitize or validate these characters before they are processed, allowing control characters to be embedded in HTTP responses. This behavior violates the fundamental security principle of input validation and demonstrates a weakness in the character encoding handling within the HTTP protocol implementation. The vulnerability specifically exploits the difference between how UTF-8 encoded characters are interpreted versus how they are validated, creating a scenario where legitimate security protections can be bypassed through carefully crafted Unicode sequences that appear harmless but contain malicious control characters. This type of vulnerability falls under CWE-129, which addresses improper validation of length of input buffers, and more specifically relates to CWE-119, which deals with weaknesses that allow for improper handling of input data.
The operational impact of CVE-2016-2216 extends beyond simple HTTP response splitting attacks, as it can enable a wide range of malicious activities including cross-site scripting attacks, cache poisoning, and session hijacking. Attackers can leverage this vulnerability to inject malicious content into HTTP responses, potentially redirecting users to malicious websites or injecting harmful scripts into web applications. The vulnerability's exploitation requires minimal effort and can be automated, making it particularly dangerous for web applications that rely on Node.js for HTTP processing. Organizations running affected Node.js versions face significant risk of data breaches and application compromise, especially those handling sensitive user information or operating in regulated environments where security compliance is mandatory. The vulnerability's presence in multiple release branches means that even organizations maintaining older Node.js versions are at risk, as the patching process requires careful version management and system updates to ensure complete protection.
Mitigation strategies for CVE-2016-2216 primarily involve immediate patching of affected Node.js installations to versions that contain the necessary security fixes, with particular attention to upgrading to Node.js 0.10.42, 0.11.16, 0.12.10, 4.3.0, or 5.6.0 respectively. Organizations should implement comprehensive monitoring to identify and remediate all systems running vulnerable Node.js versions, as the vulnerability affects both production and development environments. Additional protective measures include implementing strict HTTP header validation at the application level, using security middleware to sanitize HTTP headers, and deploying web application firewalls that can detect and block suspicious UTF-8 sequences in HTTP headers. The vulnerability aligns with ATT&CK technique T1190, which covers exploiting vulnerabilities in web applications, and demonstrates the importance of proper input validation and character encoding handling in preventing protocol-level security breaches. Organizations should also consider implementing automated vulnerability scanning tools that can detect the presence of vulnerable Node.js versions and provide real-time alerts when exposed systems are identified, as this vulnerability represents a persistent threat that can be exploited by automated attack tools.