CVE-2026-111892 in phpMyFAQ
Summary
by MITRE • 10/17/2026
phpMyFAQ 4.2.0-alpha before 4.2.0-beta lacks effective rate limiting on the unauthenticated user/password/update and user/password/reset endpoints. Unauthenticated attackers can send unlimited reset requests to flood a registered user's inbox with reset emails, exhausting mailer and server resources.
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Analysis
by VulDB Data Team • 10/17/2026
The vulnerability identified in phpMyFAQ versions prior to 4.2.0-beta represents a critical failure in access control mechanisms, specifically concerning the implementation of rate limiting on authentication-related endpoints. The affected components include the user password update and reset interfaces which are accessible without requiring initial authentication. This architectural oversight allows unauthenticated actors to interact with these services freely, bypassing standard security controls designed to prevent abuse. In modern web application security frameworks, such as those defined by OWASP, this flaw aligns directly with CWE-798: Use of Hard-coded Credentials or more accurately in this context, CWE-307: Improper Restriction of Excessive Authentication Attempts. The absence of throttling mechanisms means that the system treats every request from an unauthenticated source as equally valid and actionable, regardless of frequency or origin patterns.
From a technical perspective, the core issue lies in the lack of input validation regarding request volume for password reset operations. When a user initiates a password recovery process, the backend typically generates a token and dispatches an email to the registered address. Without rate limiting, an attacker can automate this process using simple scripts or botnets to send thousands of requests targeting specific victim accounts within a short timeframe. This capability transforms what should be a benign administrative function into a potent vector for abuse. The system fails to implement exponential backoff, CAPTCHA challenges, or IP-based throttling that are standard industry practices for mitigating automated attacks on sensitive endpoints. Consequently, the application remains vulnerable to resource exhaustion and denial of service conditions triggered by simple script execution rather than complex exploitation techniques.
The operational impact of this vulnerability extends beyond mere inconvenience for end-users. The primary consequence is a significant degradation in system availability due to mailer resource exhaustion. Email delivery services often impose strict limits on outbound messages per hour or day; flooding these APIs can cause the application's email service provider to throttle or block all outgoing traffic, effectively halting legitimate password resets and notifications across the entire platform. Furthermore, this abuse consumes substantial server CPU cycles, memory, and network bandwidth as the system processes each request, generates tokens, and attempts SMTP connections. This constitutes a Denial of Service condition where the availability of the service is compromised for all users, not just the targeted individuals receiving the spam emails. Additionally, there are secondary privacy implications as victims may experience inbox flooding which can obscure legitimate communications or cause psychological distress through harassment via automated email blasts.
Mitigation strategies must focus on implementing robust rate limiting controls at both the application and infrastructure levels. At the application layer, developers should enforce strict limits on the number of password reset requests allowed per user account within a defined time window, such as no more than three attempts per hour. Implementing CAPTCHA solutions like reCAPTCHA or hCaptcha after a single failed attempt can effectively deter automated scripts without significantly impacting legitimate user experience. From an infrastructure perspective, web application firewalls should be configured to detect and block abnormal traffic patterns associated with brute-force or flooding attacks against authentication endpoints. Regular security audits focusing on CWE-307 compliance are essential to ensure that such gaps do not persist in future releases. Upgrading immediately to version 4.2.0-beta or later is the most effective remediation as it addresses these fundamental architectural flaws by introducing proper access controls and throttling mechanisms for sensitive operations.