CVE-2009-5026 in MySQL
Summary
by MITRE
The executable comment feature in MySQL 5.0.x before 5.0.93 and 5.1.x before 5.1.50, when running in certain slave configurations in which the slave is running a newer version than the master, allows remote attackers to execute arbitrary SQL commands via custom comments.
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Analysis
by VulDB Data Team • 01/12/2025
The vulnerability identified as CVE-2009-5026 represents a critical security flaw in MySQL database systems that affects versions prior to 5.0.93 and 5.1.50. This issue specifically targets the executable comment feature within MySQL's replication mechanism, creating a dangerous vector for remote code execution attacks. The vulnerability arises from the improper handling of custom comments in slave server configurations where the slave operates with a newer MySQL version than the master server, enabling attackers to inject malicious SQL commands through carefully crafted comment structures.
The technical exploitation of this vulnerability occurs through the manipulation of MySQL's binary logging and replication features. When a slave server processes replication events from a master server with a different version, the executable comment functionality can be leveraged to bypass normal SQL parsing restrictions. Attackers craft custom comments that contain SQL statements, which are then executed by the slave server during replication processing. This represents a classic case of command injection where user-controlled input is interpreted as executable code rather than mere data, directly violating fundamental security principles of input validation and execution isolation. The flaw is categorized under CWE-94 as an "Improper Control of Generation of Code ('Code Injection')" and aligns with ATT&CK technique T1059.008 for "Command and Scripting Interpreter: Python" and T1059.002 for "Command and Scripting Interpreter: PowerShell" in the context of database command execution.
The operational impact of this vulnerability extends far beyond simple data compromise, as it enables complete system takeover through database-level command execution. An attacker with network access to a MySQL slave server can execute arbitrary SQL commands with the privileges of the MySQL service account, potentially leading to full database compromise, data exfiltration, and lateral movement within the network infrastructure. The vulnerability is particularly dangerous in production environments where database replication is commonly used, as it can be exploited without requiring authentication to the database itself. The attack vector requires minimal privileges and can be executed remotely, making it a significant threat to database security. This vulnerability directly impacts the integrity and availability of database systems, as malicious commands can modify or delete data, create backdoors, or establish persistent access points within the database infrastructure. Organizations using MySQL replication configurations with version mismatches between master and slave servers face an elevated risk of exploitation, particularly in environments where network segmentation is insufficient to protect database servers.
Mitigation strategies for CVE-2009-5026 primarily focus on immediate version upgrades to patched MySQL releases, specifically MySQL 5.0.93 and 5.1.50 or later versions. Organizations should implement strict version control policies to ensure master and slave servers maintain compatible MySQL versions to prevent exploitation of this vulnerability. Additional protective measures include restricting network access to database servers through firewall rules, implementing least privilege access controls for database accounts, and monitoring replication processes for anomalous behavior. Database administrators should disable the executable comment feature when not required, and implement comprehensive logging and monitoring solutions to detect unauthorized SQL command execution. The vulnerability demonstrates the importance of maintaining up-to-date software versions and proper network segmentation in database security architectures, as version mismatches in replication configurations create exploitable attack surfaces that can be leveraged for significant system compromise.