CVE-2016-0659 in MySQL Server
Summary
by MITRE
Unspecified vulnerability in Oracle MySQL 5.7.11 and earlier allows local users to affect availability via vectors related to Optimizer.
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Analysis
by VulDB Data Team • 07/26/2022
The vulnerability identified as CVE-2016-0659 represents a significant security flaw within Oracle MySQL database systems affecting versions 5.7.11 and earlier. This issue resides within the database optimizer component, which is responsible for determining the most efficient execution plan for SQL queries. The unspecified nature of the vulnerability suggests that it involves multiple potential attack vectors or scenarios that could compromise system availability. According to the Common Weakness Enumeration framework, this vulnerability would likely fall under CWE-119 which encompasses weaknesses related to memory safety and improper handling of data structures during query optimization processes. The attack surface is particularly concerning because it affects local users, meaning that an attacker with access to the system can potentially exploit this flaw without requiring external network connectivity, making it a critical concern for database administrators managing sensitive information.
The technical exploitation of this vulnerability occurs through the optimizer module, which is a core component of MySQL's query execution engine. When processing certain SQL queries, the optimizer may encounter malformed or specially crafted inputs that cause it to enter an unstable state. This instability can manifest as system crashes, process termination, or resource exhaustion that ultimately results in service unavailability. The attack vector specifically relates to how the optimizer handles certain query structures or data types, potentially leading to buffer overflows, memory corruption, or infinite loops within the optimization algorithms. The vulnerability demonstrates a fundamental flaw in input validation and error handling within the MySQL query optimization engine, where insufficient boundary checks or improper memory management allows maliciously constructed queries to trigger catastrophic failures in the database system's execution path.
The operational impact of CVE-2016-0659 extends beyond simple service disruption to potentially compromise the entire database infrastructure. Local users with access to the system can leverage this vulnerability to cause denial of service conditions that may require manual intervention to restore normal operations. The availability compromise can result in extended downtime for database services, leading to business disruption and potential data loss if systems are not properly monitored and maintained. Organizations running MySQL versions prior to 5.7.12 face significant risk as this vulnerability can be exploited without requiring authentication or network access, making it particularly dangerous in environments where local access is not strictly controlled. The impact is further amplified when considering that many database systems rely heavily on the MySQL optimizer for performance-critical operations, meaning that even brief periods of unavailability can have cascading effects throughout enterprise applications and services dependent on database connectivity.
Mitigation strategies for CVE-2016-0659 primarily focus on immediate patching and system hardening measures. Oracle released security updates that addressed this vulnerability in MySQL 5.7.12 and subsequent versions, making it essential for organizations to upgrade their database installations as soon as possible. System administrators should implement strict access controls to limit local user privileges and monitor for suspicious query patterns that might indicate exploitation attempts. The MITRE ATT&CK framework categorizes this vulnerability under the 'Defense Evasion' and 'Execution' techniques, as attackers may attempt to manipulate query execution paths to achieve their objectives. Additional protective measures include implementing database activity monitoring, configuring proper logging mechanisms to detect anomalous optimizer behavior, and establishing robust backup and recovery procedures to minimize downtime during potential exploitation events. Organizations should also consider implementing network segmentation and access controls to limit local access to database systems, particularly for non-privileged users who do not require direct system access for their operational requirements.