CVE-2007-0107 in WordPress
Summary
by MITRE
WordPress before 2.0.6, when mbstring is enabled for PHP, decodes alternate character sets after escaping the SQL query, which allows remote attackers to bypass SQL injection protection schemes and execute arbitrary SQL commands via multibyte charsets, as demonstrated using UTF-7.
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Analysis
by VulDB Data Team • 07/13/2019
This vulnerability exists in WordPress versions prior to 2.0.6 where the application fails to properly handle multibyte character sets when the mbstring PHP extension is enabled. The flaw stems from a critical order of operations error in the SQL query escaping mechanism. When WordPress processes user input containing multibyte characters, it first applies SQL escaping to the input data and then subsequently decodes alternate character sets using mbstring functions. This sequence creates a window of opportunity where maliciously crafted UTF-7 encoded input can bypass the SQL escaping protection and execute arbitrary SQL commands. The vulnerability specifically leverages the interaction between PHP's mbstring extension and WordPress's input sanitization routines, where the character set decoding occurs after the SQL escaping has already been applied, effectively neutralizing the protective measures. This represents a classic example of improper input validation and sanitization that violates security principles outlined in CWE-89, which addresses SQL injection vulnerabilities. The attack vector demonstrates how seemingly benign multibyte character handling can be exploited to circumvent database security controls, making it particularly dangerous as it can be executed remotely without requiring elevated privileges. The vulnerability is classified under ATT&CK technique T1190, which covers exploitation of vulnerabilities in web applications, and T1071.004, which involves application layer protocols such as HTTP. The flaw affects the integrity and confidentiality of database operations by allowing unauthorized access to sensitive information and potential data manipulation. The root cause lies in the improper handling of character encoding transformations within the WordPress core code, where the order of operations between input sanitization and character set processing creates an exploitable gap. This vulnerability impacts the overall security posture of WordPress installations by undermining the fundamental database protection mechanisms that are expected to prevent unauthorized command execution. The security implications extend beyond simple data theft to include potential system compromise through database manipulation and privilege escalation. Organizations using affected WordPress versions should immediately implement patches and updates to address this vulnerability. The mitigation strategy involves ensuring that WordPress is updated to version 2.0.6 or later, where the input processing order has been corrected to prevent character set decoding from occurring after SQL escaping. Additionally, administrators should disable the mbstring extension if multibyte character support is not required, or implement additional input validation measures to further harden the application against similar attacks. This vulnerability highlights the importance of proper sequence handling in security-sensitive code and demonstrates how seemingly unrelated PHP extensions can create exploitable conditions when integrated into web application frameworks. The flaw underscores the necessity of thorough security testing that includes edge cases involving multibyte character sets and proper input sanitization sequences to prevent such bypass scenarios from occurring in production environments.