CVE-2021-24299 in ReDi Restaurant Reservation Plugin
Summary
by MITRE • 05/17/2021
The ReDi Restaurant Reservation WordPress plugin before 21.0426 provides the functionality to let users make restaurant reservations. These reservations are stored and can be listed on an 'Upcoming' page provided by the plugin. An unauthenticated user can fill in the form to make a restaurant reservation. The form to make a restaurant reservation field called 'Comment' does not use proper input validation and can be used to store XSS payloads. The XSS payloads will be executed when the plugin user goes to the 'Upcoming' page, which is an external website https://upcoming.reservationdiary.eu/ loaded in an iframe, and the stored reservation with XSS payload is loaded.
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Analysis
by VulDB Data Team • 05/03/2025
The CVE-2021-24299 vulnerability affects the ReDi Restaurant Reservation WordPress plugin version 21.0426 and earlier, presenting a critical cross-site scripting risk that exploits improper input validation mechanisms within the plugin's reservation system. This vulnerability specifically targets the Comment field in the reservation form, which lacks adequate sanitization and validation controls, allowing malicious actors to inject malicious scripts that persist within the plugin's data storage system. The flaw manifests when unauthenticated users submit reservation requests through the plugin's frontend interface, where the Comment field becomes a vector for persistent XSS attacks.
The technical exploitation of this vulnerability follows a specific attack pattern that leverages the plugin's data handling architecture. When users submit reservations, the Comment field data is stored without proper sanitization, creating a persistent storage vector for malicious payloads. The vulnerability becomes active when plugin administrators access the 'Upcoming' page, which displays reservations in an iframe loaded from the external domain https://upcoming.reservationdiary.eu/. This external iframe serves as the execution environment where stored XSS payloads are rendered, potentially compromising administrator sessions and enabling further attack vectors.
The operational impact of this vulnerability extends beyond simple script execution, representing a significant risk to the security posture of WordPress installations using the affected plugin. Attackers can leverage this vulnerability to execute malicious scripts in the context of administrator sessions, potentially leading to complete compromise of the affected WordPress site. The vulnerability's persistence through storage means that once exploited, malicious payloads remain active until manually removed from the database, creating a long-term threat vector. Additionally, the external iframe loading mechanism creates a complex attack surface where malicious code execution can occur in a trusted context, potentially bypassing standard browser security mechanisms.
Security professionals should recognize this vulnerability as a classic example of CWE-79: Cross-site Scripting, specifically manifesting as a persistent XSS attack within a web application's data storage layer. The attack pattern aligns with ATT&CK technique T1566.001: Phishing via Social Engineering, where users are tricked into submitting malicious content that then executes in the context of privileged users. The vulnerability also demonstrates characteristics of T1059.001: Command and Scripting Interpreter, as attackers can execute arbitrary JavaScript code through the Comment field. Organizations should implement immediate mitigations including plugin updates to version 21.0426 or later, input validation hardening for all user-submitted data fields, and regular security audits of third-party plugins to prevent similar vulnerabilities from being exploited.
The remediation approach for this vulnerability requires a multi-layered strategy that addresses both immediate protection and long-term security improvements. The primary solution involves updating the ReDi Restaurant Reservation plugin to version 21.0426 or higher, which includes proper input validation and sanitization mechanisms for the Comment field. System administrators should also implement Content Security Policy headers to limit script execution capabilities, particularly for the iframe loading external content. Database-level input sanitization should be enforced for all user-submitted data, with proper HTML entity encoding and script tag removal. Additionally, organizations should conduct regular security assessments of their WordPress plugin ecosystem, implementing automated scanning tools to identify outdated or vulnerable components. The vulnerability underscores the importance of proper input validation and output encoding practices, as outlined in OWASP Top 10 2021 Category A03: Injection, where inadequate input sanitization creates persistent security risks that can compromise entire applications through seemingly innocuous user interface elements.