CVE-2024-9266 in Express.js
Summary
by MITRE • 10/03/2024
URL Redirection to Untrusted Site ('Open Redirect') vulnerability in Express. This vulnerability affects the use of the Express Response object. This issue impacts Express: from 3.4.5 before 4.0.0.
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Analysis
by VulDB Data Team • 01/30/2026
The CVE-2024-9266 vulnerability represents a critical open redirect flaw within the Express web framework that enables malicious actors to manipulate URL redirection behavior in applications built on this platform. This vulnerability specifically targets the Express Response object and affects versions from 3.4.5 through the pre-release version of 4.0.0, creating a significant security risk for web applications that rely on proper URL handling and user redirection mechanisms. The flaw allows attackers to craft malicious URLs that redirect users to arbitrary external domains, potentially enabling phishing attacks, credential theft, or other malicious activities. The vulnerability exists because the framework fails to adequately validate or sanitize redirect URLs, permitting untrusted inputs to influence the destination of user navigation. This issue directly impacts the security posture of web applications by undermining the trust relationship between the application and its users, as users may be unknowingly redirected to malicious sites without proper security warnings or validation.
The technical implementation of this vulnerability stems from insufficient input validation within the Express Response object's redirect functionality. When applications use the redirect method to handle user navigation, the framework does not properly sanitize the destination URL to ensure it originates from a trusted source. This allows attackers to inject malicious URLs that bypass normal security checks, particularly when the application uses user-supplied input to determine redirect destinations. The flaw operates at the application layer and can be exploited through various vectors including crafted HTTP requests, parameter manipulation, or injection techniques that leverage the framework's redirect handling capabilities. The vulnerability's impact is amplified when applications use redirects for authentication flows, session management, or user navigation, as these scenarios provide ideal conditions for attackers to intercept user credentials or perform unauthorized actions. According to CWE standards, this vulnerability maps to CWE-601, which specifically addresses URL redirection to untrusted sites, and aligns with ATT&CK techniques that involve credential access through phishing or social engineering methods.
The operational impact of CVE-2024-9266 extends beyond simple redirection to encompass broader security implications for web applications and user trust. Attackers can exploit this vulnerability to create convincing phishing campaigns by redirecting users to malicious sites that appear legitimate, potentially stealing session cookies, login credentials, or personal information. The vulnerability is particularly dangerous in environments where applications handle sensitive data or authentication flows, as it can serve as a stepping stone for more sophisticated attacks including privilege escalation or data exfiltration. Organizations using affected Express versions face increased risk of security incidents, potential regulatory compliance violations, and damage to user trust. The vulnerability affects not just individual applications but entire ecosystems that depend on Express framework components, making it a widespread concern for developers and security teams. Additionally, the issue can complicate security audits and penetration testing efforts, as the open redirect behavior may mask other underlying security problems or provide attackers with additional attack surface. The vulnerability's persistence across multiple versions of the framework indicates a fundamental design flaw that requires immediate attention and remediation to protect deployed applications from exploitation.
Organizations should prioritize immediate remediation by upgrading to Express versions 4.0.0 or later where this vulnerability has been addressed through improved input validation and sanitization mechanisms. Security teams should implement comprehensive network monitoring to detect suspicious redirect patterns and conduct thorough code reviews to identify all instances where the redirect functionality is used with user-supplied inputs. Additional mitigations include implementing strict URL validation policies, using allowlists for redirect destinations, and deploying web application firewalls that can detect and block malicious redirect attempts. Organizations should also consider implementing security headers such as Content Security Policy to prevent unauthorized redirection and enhance overall application security. Regular security assessments and vulnerability scanning should be conducted to ensure that no other components within the application architecture are susceptible to similar issues. The remediation process should include comprehensive testing to verify that redirect functionality operates correctly while maintaining security controls, ensuring that legitimate redirection behavior is preserved while eliminating the vulnerability. This vulnerability underscores the importance of proper input validation and the need for continuous security monitoring in modern web application development practices.