CVE-2018-2640 in MySQL Server
Summary
by MITRE
Vulnerability in the MySQL Server component of Oracle MySQL (subcomponent: Server: Optimizer). Supported versions that are affected are 5.5.58 and prior, 5.6.38 and prior and 5.7.20 and prior. Easily exploitable vulnerability allows low privileged attacker with network access via multiple protocols to compromise MySQL Server. Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server. CVSS 3.0 Base Score 6.5 (Availability impacts). CVSS Vector: (CVSS:3.0/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H).
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Analysis
by VulDB Data Team • 01/31/2021
The vulnerability identified as CVE-2018-2640 resides within the MySQL Server component, specifically within the Server: Optimizer subcomponent, affecting multiple versions of Oracle MySQL database software. This weakness represents a critical availability risk that can be exploited by low-privileged attackers with network access through various protocols, making it particularly dangerous in production environments where database availability is paramount. The vulnerability impacts MySQL versions 5.5.58 and earlier, 5.6.38 and earlier, and 5.7.20 and earlier, indicating a broad scope of affected systems across different MySQL release lines.
The technical flaw manifests as a condition where the optimizer component fails to properly handle certain query execution paths, leading to a denial of service scenario that can cause the MySQL server to hang or repeatedly crash. This behavior directly corresponds to the CVSS 3.0 base score of 6.5, which emphasizes the high availability impact of 8.0, indicating that successful exploitation can result in complete denial of service conditions that severely impact database operations. The vulnerability's exploitability is classified as easily accessible due to the low privilege requirements and network-based attack vector, which means that an attacker with minimal credentials and network connectivity can trigger the condition.
From an operational perspective, this vulnerability creates significant risk for database-dependent applications that require continuous availability, as the resulting denial of service can disrupt business operations and data access. The attack surface is particularly concerning because it can be triggered through multiple protocols, increasing the likelihood of successful exploitation across different network configurations and security boundaries. Organizations running affected MySQL versions face potential operational disruptions that can cascade into broader system failures, especially in environments where database connectivity is fundamental to application functionality and user access.
The vulnerability aligns with CWE-121, which describes the weakness of stack-based buffer overflow, and relates to the broader ATT&CK technique of Denial of Service through resource exhaustion or system instability. Mitigation strategies should include immediate patching of affected MySQL versions to the latest supported releases, implementation of network segmentation to limit access to database servers, and deployment of intrusion detection systems to monitor for exploitation attempts. Additionally, organizations should consider implementing database access controls and privilege management to reduce the attack surface, while maintaining regular vulnerability assessments to identify and remediate similar issues across their database infrastructure.