CVE-2002-1168 in Websphere Caching Proxy Server
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in IBM Web Traffic Express Caching Proxy Server 3.6 and 4.x before 4.0.1.26 allows remote attackers to execute script as other users via an HTTP request that contains an Location: header with a "%0a%0d" (CRLF) sequence, which echoes the Location as an HTTP header in the server response.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/07/2025
This cross-site scripting vulnerability exists in IBM Web Traffic Express Caching Proxy Server versions 3.6 and 4.x prior to 4.0.1.26, representing a critical security flaw that enables remote attackers to execute malicious scripts against unsuspecting users. The vulnerability stems from improper input validation and sanitization of HTTP headers, specifically the Location header, which is processed without adequate security measures to prevent code injection attacks. The flaw manifests when an attacker crafts an HTTP request containing a Location header with a "%0a%0d" (CRLF) sequence that gets echoed back in the server response, creating an opportunity for XSS exploitation.
The technical mechanism of this vulnerability operates through the manipulation of HTTP response headers where the proxy server fails to properly sanitize user-supplied input before incorporating it into the response. When the Location header contains the CRLF sequence, the server processes this input and includes it in the HTTP response headers without proper encoding or validation, allowing malicious scripts to be injected and executed in the context of other users' browsers. This represents a classic example of insecure handling of user input in web applications, specifically violating the principle of input sanitization and output encoding that forms the foundation of secure web development practices. The vulnerability aligns with CWE-79, which describes cross-site scripting flaws, and demonstrates how improper handling of HTTP headers can create attack vectors that bypass traditional security controls.
The operational impact of this vulnerability is significant as it allows attackers to perform session hijacking, steal user credentials, deface web pages, or redirect users to malicious sites. Since the vulnerability affects the caching proxy server, it can potentially impact multiple users and applications that rely on the proxy for traffic management, making it particularly dangerous in enterprise environments where centralized proxy servers are commonly deployed. Attackers can leverage this flaw to execute arbitrary JavaScript code in victims' browsers, potentially leading to complete compromise of user sessions and unauthorized access to sensitive information. The vulnerability also demonstrates how proxy servers, which typically serve as security intermediaries, can themselves become attack vectors when not properly secured against input manipulation.
Organizations should immediately apply the vendor-provided patch for IBM Web Traffic Express Caching Proxy Server version 4.0.1.26 or higher to remediate this vulnerability. In the interim, administrators should implement network-level controls to monitor and filter HTTP requests containing suspicious CRLF sequences in headers, though such measures are not foolproof. The vulnerability also highlights the importance of proper input validation across all network components, particularly those that process HTTP headers, as specified in the OWASP Top Ten security principles. Additionally, organizations should consider implementing Content Security Policy headers and other defensive measures to limit the impact of potential XSS attacks. This vulnerability serves as a reminder that even security-critical infrastructure components like proxy servers must undergo rigorous security testing and validation to prevent exploitation through seemingly simple input manipulation techniques.