CVE-2003-1586 in WebExpert
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in WebExpert allows remote attackers to inject arbitrary web script or HTML via a crafted User-Agent HTTP header.
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Analysis
by VulDB Data Team • 04/30/2026
The vulnerability identified as CVE-2003-1586 represents a classic cross-site scripting flaw within the WebExpert web application framework. This security weakness resides in the application's improper handling of User-Agent HTTP headers, creating an avenue for malicious actors to execute arbitrary web scripts or HTML code within the context of other users' browsers. The vulnerability stems from the application's failure to adequately sanitize or validate input received through the User-Agent header, which is typically used by web browsers to identify themselves to servers. When a malicious User-Agent string containing embedded script tags is processed by the WebExpert application, the system fails to properly escape or filter these potentially harmful elements before rendering them in the web interface.
This particular XSS vulnerability operates at the client-side execution level and falls under the CWE-79 category of Cross-Site Scripting, which specifically addresses the injection of malicious scripts into web applications that are intended to be trusted by users. The attack vector leverages the HTTP User-Agent header, a standard component of web requests that browsers automatically include in their communication with web servers. The vulnerability's classification as a remote attack means that malicious actors can exploit this weakness without requiring physical access to the target system or any local privileges, making it particularly dangerous for widespread exploitation. The WebExpert application's insufficient input validation and output encoding mechanisms create an environment where attacker-controlled data can be seamlessly integrated into the application's dynamic content generation process.
The operational impact of this vulnerability extends beyond simple script execution, potentially enabling attackers to perform session hijacking, deface web pages, steal sensitive user data, or redirect users to malicious websites. When a victim's browser processes a web page that contains the injected malicious script, the script executes within the victim's browser context with the privileges of the victim's session. This allows attackers to access session cookies, modify page content, or even redirect users to phishing sites that can harvest credentials. The vulnerability's persistence depends on how the WebExpert application displays the User-Agent information, which may be shown in administrative interfaces, user activity logs, or other areas where this header information is rendered to authenticated users. The attack scenario becomes particularly concerning when administrators or other privileged users view web application logs or user activity reports that contain the malicious User-Agent strings, as these users would be subject to the injected scripts.
Mitigation strategies for CVE-2003-1586 should focus on implementing comprehensive input validation and output encoding mechanisms throughout the WebExpert application's codebase. The primary defense involves sanitizing all HTTP headers, including the User-Agent field, by removing or escaping potentially dangerous characters such as angle brackets, script tags, and other HTML elements that could be interpreted as executable code. Implementing proper content security policies and using secure coding practices that enforce strict input validation can prevent the injection of malicious content. Organizations should also consider implementing web application firewalls that can detect and block suspicious User-Agent patterns, as well as conducting regular security audits to identify similar vulnerabilities in other input handling mechanisms. The remediation approach aligns with ATT&CK technique T1566.001 which involves the exploitation of web application vulnerabilities, and the mitigation strategies should follow the principle of least privilege by ensuring that only necessary data is processed and displayed from user-provided headers. Additionally, regular security training for developers on secure coding practices and the implementation of automated security testing tools can help prevent similar vulnerabilities from being introduced in future versions of the WebExpert framework.