CVE-2007-2401 in Mac OS X
Summary
by MITRE
CRLF injection vulnerability in WebCore in Apple Mac OS X 10.3.9, 10.4.9 and later, and iPhone before 1.0.1, allows remote attackers to inject arbitrary HTTP headers via LF characters in an XMLHttpRequest request, which are not filtered when serializing headers via the setRequestHeader function. NOTE: this issue can be leveraged for cross-site scripting (XSS) attacks.
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Analysis
by VulDB Data Team • 04/04/2025
The CVE-2007-2401 vulnerability represents a critical cross-site scripting attack vector that emerged in Apple's WebCore component affecting multiple operating systems and mobile platforms. This vulnerability stems from insufficient input validation within the XMLHttpRequest implementation, specifically in how the setRequestHeader function processes header data. The flaw allows attackers to inject malicious HTTP headers through line feed characters that bypass normal filtering mechanisms during header serialization. The vulnerability affects Apple Mac OS X versions 10.3.9 through 10.4.9 and later, as well as iPhone operating systems prior to version 1.0.1, demonstrating the widespread impact across Apple's ecosystem. The issue resides in the core web rendering engine that handles HTTP communication, making it particularly dangerous as it operates at a fundamental level of web application processing.
The technical exploitation of this vulnerability occurs when an attacker crafts a malicious XMLHttpRequest request containing line feed characters that are not properly sanitized during header processing. During the serialization phase of header data, these unfiltered line feed characters are interpreted as header terminators, allowing attackers to inject additional HTTP headers into the request. This injection capability enables attackers to manipulate the HTTP request structure in ways that can bypass security controls and potentially execute malicious code within the victim's browser context. The vulnerability operates under CWE-113, which specifically addresses "Improper Neutralization of CRLF Sequences in HTTP Headers" and maps directly to the ATT&CK technique T1559.001 for "Component Interaction: Command and Scripting Interpreter". The flaw essentially creates a condition where the application fails to properly validate and sanitize header data before incorporating it into HTTP requests, creating a pathway for header injection attacks.
The operational impact of CVE-2007-2401 extends beyond simple header injection, as it provides a foundation for more sophisticated attacks including cross-site scripting exploitation. When combined with other vulnerabilities or attack vectors, this CRLF injection flaw can enable attackers to manipulate web application behavior, redirect users to malicious sites, or inject malicious content that executes in the victim's browser. The vulnerability is particularly concerning because it affects widely used Apple platforms including desktop operating systems and mobile devices, providing attackers with access to a broad user base. The impact is amplified by the fact that XMLHttpRequest is a fundamental web technology used extensively in modern web applications, making the exploitation surface particularly large. Security researchers have noted that the vulnerability can be leveraged to create persistent XSS attacks that can compromise user sessions and exfiltrate sensitive data from web applications.
Mitigation strategies for CVE-2007-2401 require both immediate patching and architectural considerations to prevent similar vulnerabilities. Apple addressed this issue through system updates that implemented proper input sanitization and filtering of line feed characters in HTTP header processing. Organizations should ensure that all affected systems receive the appropriate security updates immediately, as the vulnerability remains exploitable in unpatched environments. Additional protective measures include implementing strict input validation at multiple layers of the application architecture, configuring web application firewalls to detect and block suspicious header patterns, and establishing robust header sanitization routines. The vulnerability underscores the importance of proper input validation and sanitization practices as outlined in the OWASP Top Ten security principles, particularly focusing on preventing injection attacks through proper data validation and encoding techniques. Network administrators should also monitor for suspicious HTTP header patterns that may indicate exploitation attempts and implement logging mechanisms to track potential abuse of this vulnerability.