CVE-2026-109573 in phpMyFAQ
Summary
by MITRE • 10/13/2026
phpMyFAQ before 4.1.9 contains an SQL injection vulnerability in PdoMysql::escape(), which escapes single quotes with backslashes that are treated literally when MySQL or MariaDB runs in NO_BACKSLASH_ESCAPES mode. Unauthenticated attackers can send a Unicode right single quotation mark in the search parameter of api/autocomplete, which is normalized to an ASCII quote, to read credentials and configuration secrets, modify records, or drop tables.
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Analysis
by VulDB Data Team • 10/13/2026
The vulnerability identified in phpMyFAQ versions prior to 4.1.9 represents a critical SQL injection flaw rooted in improper input sanitization within the PdoMysql::escape() function. This specific implementation detail relies on escaping single quotes by prepending them with backslashes, a method that is standard for MySQL and MariaDB when operating under default configuration settings. However, this approach fails to account for environments where the database server runs with the NO_BACKSLASH_ESCAPES SQL mode enabled. In such configurations, the database engine treats backslash characters as literal data rather than escape sequences, rendering the sanitization mechanism ineffective against crafted payloads that exploit this discrepancy.
The attack vector is accessible via an unauthenticated endpoint, specifically the api/autocomplete route which accepts a search parameter. An attacker can leverage Unicode normalization features to bypass basic input filters by submitting a Unicode right single quotation mark character instead of a standard ASCII apostrophe. The application processes this input and normalizes it into an ASCII quote before passing it to the database layer. Because the escape function adds backslashes only after or during processing, and because the underlying database ignores these backslashes due to its specific mode configuration, the injected quotes successfully break out of their intended string context within the SQL query structure.
This lack of robust parameterization allows unauthenticated attackers to execute arbitrary SQL commands against the backend database. The operational impact is severe, as it grants full read and write access to the application's data store depending on the privileges assigned to the database user account used by phpMyFAQ. Attackers can extract sensitive information including administrator credentials, configuration secrets, and other proprietary data stored within the system. Furthermore, the vulnerability permits destructive actions such as modifying existing records or dropping entire tables, which could lead to complete service disruption and loss of critical content managed through the FAQ platform.
From a classification perspective, this issue aligns with CWE-89 Improper Neutralization of Special Elements used in an SQL Command, commonly known as SQL Injection. The exploitation technique involves manipulating input parameters to alter query logic, falling under ATT&CK tactic T1059 Command and Scripting Interpreter if the database allows command execution via extensions like UDF, or more broadly within data exfiltration techniques found in TA0009 Collection. To mitigate this vulnerability, administrators must upgrade phpMyFAQ to version 4.1.9 or later where the issue has been resolved by implementing proper prepared statements with bound parameters rather than relying on manual string escaping. Additionally, ensuring that database connections do not operate under NO_BACKSLASH_ESCAPES mode when using legacy escape functions can provide a secondary layer of defense, although parameterized queries remain the industry standard for preventing SQL injection attacks regardless of server configuration settings.