CVE-2025-12166 in Appointment Booking Calendar Plugin
Summary
by MITRE • 01/15/2026
The Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin plugin for WordPress is vulnerable to blind SQL Injection via the `order` and `append_where_sql` parameters in all versions up to, and including, 1.6.9.9 due to insufficient escaping on the user supplied parameter and lack of sufficient preparation on the existing SQL query. This makes it possible for unauthenticated attackers to append additional SQL queries into already existing queries that can be used to extract sensitive information from the database.
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Analysis
by VulDB Data Team • 01/17/2026
The vulnerability identified as CVE-2025-12166 affects the Appointment Booking Calendar plugin for WordPress, specifically targeting versions up to and including 1.6.9.9. This blind SQL injection vulnerability arises from inadequate input sanitization and parameter handling within the plugin's database query execution logic. The flaw manifests through the `order` and `append_where_sql` parameters, which are processed without proper escaping mechanisms, allowing malicious actors to manipulate the underlying SQL queries through crafted input. The vulnerability is classified under CWE-89 as SQL injection, with the blind variant indicating that attackers cannot directly observe query results but can infer information through indirect means such as response timing or conditional responses.
The technical exploitation of this vulnerability enables unauthenticated attackers to inject malicious SQL code into existing database queries through the vulnerable parameters. When the plugin processes user-supplied data in the `order` and `append_where_sql` fields, it fails to implement proper prepared statements or parameterized queries, creating a pathway for attackers to append additional SQL commands to the original query structure. This allows for the extraction of sensitive database information including user credentials, personal data, and plugin configuration details. The vulnerability's impact is amplified by the fact that it does not require authentication, making it particularly dangerous as any visitor to the WordPress site could potentially exploit this flaw.
The operational consequences of this vulnerability extend beyond simple data theft, as successful exploitation could lead to complete database compromise and potential system takeover. Attackers could leverage the blind SQL injection to enumerate database schemas, extract user accounts with administrative privileges, and potentially escalate their access to gain full control over the WordPress installation. The vulnerability affects the core functionality of the appointment booking system, potentially disrupting business operations while simultaneously providing attackers with a persistent foothold within the target environment. This type of vulnerability is particularly concerning in the context of ATT&CK framework's T1071.004 technique, where adversaries may use SQL injection to gain access to sensitive data and establish persistence within web applications.
Mitigation strategies for CVE-2025-12166 should prioritize immediate plugin updates to versions that address the SQL injection vulnerability through proper input validation and parameterized query implementation. Organizations should also implement web application firewalls to monitor and block suspicious SQL injection patterns targeting the affected parameters. Database access controls should be reviewed to ensure least privilege principles are enforced, and regular security audits should be conducted to identify similar vulnerabilities in other plugins or themes. Additionally, implementing proper input sanitization and output escaping mechanisms within the application code can prevent similar issues from occurring in future development cycles, aligning with industry best practices for secure coding standards and OWASP Top Ten prevention techniques.