CVE-2023-48828 in Time Slots Booking Calendar
Summary
by MITRE • 12/07/2023
Time Slots Booking Calendar 4.0 is vulnerable to Multiple Stored Cross-Site Scripting (XSS) issues via the name, plugin_sms_api_key, plugin_sms_country_code, calendar_id, title, country name, or customer_name parameter.
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Analysis
by VulDB Data Team • 03/02/2026
The Time Slots Booking Calendar plugin version 4.0 presents a critical security vulnerability classified as multiple stored cross-site scripting flaws that can be exploited by malicious actors to inject persistent malicious scripts into the application's database. This vulnerability affects several input parameters including name, plugin_sms_api_key, plugin_sms_country_code, calendar_id, title, country name, and customer_name fields, creating multiple attack vectors for potential exploitation. The stored nature of these XSS vulnerabilities means that malicious payloads injected through these parameters will persist in the database and execute whenever legitimate users access the affected pages, making the threat particularly dangerous for persistent attacks.
The technical implementation of this vulnerability stems from insufficient input validation and output sanitization within the plugin's data handling mechanisms. When user-provided data is stored without proper sanitization and subsequently rendered back to users without appropriate encoding, attackers can inject malicious javascript code that executes in the context of other users' browsers. This weakness aligns with CWE-79 which defines cross-site scripting as the improper handling of input data that leads to arbitrary code execution in user browsers. The vulnerability affects the plugin's core functionality where user data is collected for booking calendar operations, SMS integration, and customer management features, creating a comprehensive attack surface that spans multiple operational domains.
The operational impact of this vulnerability extends beyond simple script execution as it can enable attackers to perform a wide range of malicious activities including session hijacking, credential theft, data exfiltration, and privilege escalation within the affected application environment. Attackers could leverage these stored XSS vulnerabilities to establish persistent access to the calendar system, potentially compromising sensitive booking data, customer information, and integration keys such as the SMS API key which could be exploited for unauthorized messaging services. The vulnerability's presence in parameters related to calendar_id and title suggests that even administrative functions within the booking system could be compromised, potentially allowing attackers to manipulate calendar events and access restricted administrative interfaces.
Security professionals should implement immediate mitigations including comprehensive input validation and output encoding for all user-supplied parameters across the affected plugin components. The recommended approach involves sanitizing all incoming data using context-appropriate encoding techniques and implementing proper content security policies to prevent script execution. Organizations should also consider implementing web application firewalls with XSS detection capabilities and conducting thorough security assessments of the plugin's data handling processes. The vulnerability demonstrates the importance of following secure coding practices as outlined in the OWASP Top Ten and ATT&CK framework's T1566 technique for credential access through exploitation of web application vulnerabilities. Regular security updates and patch management procedures should be enforced to address such vulnerabilities promptly, as the stored nature of XSS attacks means that once exploited, malicious payloads can persist and affect multiple users over extended periods, making early detection and remediation critical for maintaining application integrity and user data protection.