CVE-2018-10100 in WordPress
Summary
by MITRE
Before WordPress 4.9.5, the redirection URL for the login page was not validated or sanitized if forced to use HTTPS.
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Analysis
by VulDB Data Team • 02/28/2023
The vulnerability identified as CVE-2018-10100 represents a critical security flaw in WordPress versions prior to 4.9.5 that specifically affects the authentication mechanism and session management processes. This issue stems from inadequate input validation within the WordPress core codebase, where the system failed to properly sanitize or validate redirection URLs during the login process when forced to use HTTPS. The flaw occurs in the context of web application security where proper input sanitization is essential to prevent malicious actors from exploiting authentication flows. The vulnerability directly impacts the integrity of the WordPress authentication system by allowing unauthorized redirection that could potentially lead to phishing attacks or other malicious activities.
The technical implementation of this vulnerability resides in the WordPress core authentication handling code where the system processes redirect URLs after successful login attempts. When WordPress forces HTTPS connections for login pages, the application should validate that any redirect URL originates from a trusted source within the same domain or explicitly allowed domains. However, the flawed implementation fails to perform this validation, creating an attack surface where malicious actors could craft specially formatted URLs that would redirect users to unauthorized third-party domains. This represents a classic case of improper input validation and sanitization that aligns with CWE-20, which specifically addresses "Improper Input Validation" in software security contexts. The vulnerability operates at the application layer and affects the authentication and session management components of the WordPress framework.
The operational impact of this vulnerability extends beyond simple redirection manipulation and creates significant risks for WordPress site administrators and users. Attackers could exploit this flaw by crafting malicious login URLs that would redirect users to phishing sites or malicious domains upon successful authentication, effectively bypassing security measures designed to protect user credentials. This type of attack falls under the ATT&CK framework's credential access and defense evasion techniques where adversaries leverage authentication bypasses to maintain persistent access. The vulnerability particularly affects WordPress installations that rely on forced HTTPS for security reasons, making it a critical concern for organizations that implement strict security policies around authentication flows and session management. The attack vector typically involves social engineering elements where users are directed to malicious URLs through phishing campaigns or compromised links.
Mitigation strategies for CVE-2018-10100 require immediate patching of affected WordPress installations to version 4.9.5 or later where the validation has been properly implemented. System administrators should ensure that all WordPress instances are updated to the latest stable releases and that proper security monitoring is in place to detect unusual redirection patterns. The implementation of Content Security Policy headers and proper URL validation mechanisms within the web application firewall can provide additional layers of protection. Organizations should also conduct regular security audits of their authentication flows and implement proper monitoring for unauthorized redirection attempts. This vulnerability highlights the importance of proper input validation in web applications and demonstrates how seemingly minor security gaps can create significant risks for user authentication systems. The fix implemented in WordPress 4.9.5 specifically addresses the validation of redirect URLs by ensuring that any forced HTTPS redirection maintains proper domain validation and prevents cross-site redirection attacks.