CVE-2023-48838 in Appointment Scheduler
Summary
by MITRE • 12/07/2023
Appointment Scheduler 3.0 is vulnerable to Multiple HTML Injection issues via the SMS API Key or Default Country Code.
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Analysis
by VulDB Data Team • 03/02/2026
The Appointment Scheduler 3.0 plugin presents a significant security vulnerability classified as multiple HTML injection flaws within its SMS API Key and Default Country Code functionality. This vulnerability stems from inadequate input validation and sanitization mechanisms that fail to properly filter user-supplied data before processing or rendering within web contexts. The flaw allows attackers to inject malicious HTML content through these specific parameters, potentially enabling various malicious activities including cross-site scripting attacks and unauthorized data manipulation.
The technical implementation of this vulnerability occurs when the plugin processes SMS API Key or Default Country Code values without proper sanitization of special characters and HTML markup. When these parameters are accepted from external sources or user inputs, the system fails to validate their contents against established security patterns. This lack of input filtering creates an environment where attackers can embed malicious scripts or HTML elements that will be executed in the context of other users' browsers or system processes. The vulnerability manifests when the application renders these unfiltered values in web pages or API responses without appropriate encoding or escaping mechanisms.
The operational impact of this vulnerability extends beyond simple data corruption or display issues. Attackers can leverage these HTML injection points to perform session hijacking, steal user credentials, manipulate application behavior, or redirect users to malicious websites. The SMS API Key injection could potentially allow unauthorized access to SMS services or enable attackers to modify API configurations that control message delivery. Meanwhile, the Default Country Code injection could be used to manipulate geographic data or influence routing decisions within the application's communication infrastructure. These vulnerabilities create opportunities for attackers to compromise user privacy, disrupt service availability, and potentially escalate privileges within the system.
Security mitigation strategies should focus on implementing comprehensive input validation and sanitization mechanisms throughout the application's data processing pipeline. All user-supplied inputs must be validated against whitelisted character sets and properly escaped or encoded before being rendered in HTML contexts. The implementation should follow established security frameworks such as those recommended by the CWE database which categorizes this issue under CWE-79 - Improper Neutralization of Input During Web Page Generation. Additionally, defense-in-depth measures including Content Security Policy (CSP) headers, regular security code reviews, and automated input validation testing should be implemented. Organizations should also consider implementing the ATT&CK framework's mitigation strategies for web application vulnerabilities, particularly focusing on input validation controls and privilege separation to limit the potential impact of such injection attacks. Regular security assessments and vulnerability scanning should be conducted to identify similar issues across the entire application stack and ensure that proper security controls remain effective against evolving attack vectors.