CVE-2018-2668 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-2018-2668 resides within the MySQL Server component, specifically within the Server: Optimizer subcomponent of Oracle MySQL database systems. This flaw affects multiple version ranges including 5.5.58 and earlier, 5.6.38 and earlier, and 5.7.20 and earlier releases, making it a widespread concern across several major MySQL branches. The vulnerability classification as easily exploitable indicates that attackers with minimal privileges and network access can leverage this weakness, representing a significant security risk for database environments that have not been patched. The CVSS 3.0 scoring of 6.5 reflects the severity level with a base score emphasizing availability impacts at a high level, specifically indicating that successful exploitation can lead to complete denial of service conditions.
The technical nature of this vulnerability stems from improper handling within the query optimizer module of MySQL Server, which is responsible for determining the most efficient execution plan for database queries. When processing certain malformed or specially crafted queries, the optimizer fails to properly validate input parameters, leading to memory corruption or unexpected behavior that results in system instability. This flaw specifically manifests as a condition where the database server becomes unresponsive or experiences frequent crashes, effectively rendering the database service unavailable to legitimate users and applications. The vulnerability operates through multiple network protocols, increasing its attack surface and making it particularly dangerous in environments where database services are accessible over standard network connections.
The operational impact of CVE-2018-2668 extends beyond simple service disruption, as it can lead to complete system unavailability that affects business operations and data accessibility. Organizations relying on MySQL databases for critical applications face potential downtime that can result in financial losses, service interruptions, and damage to customer relationships. The low privilege requirement means that even users with minimal database access rights can exploit this vulnerability, making it particularly concerning for environments where access controls may not be strictly enforced. Additionally, the repetitive nature of the crashes can make the system unstable and difficult to recover from, potentially requiring complete service restarts or even system reinstallation in severe cases.
Mitigation strategies for this vulnerability primarily focus on immediate patching of affected MySQL installations to the latest available versions that contain the necessary security fixes. Organizations should prioritize updating their MySQL servers to versions that have been certified as free from this vulnerability, typically those released after the patching timeline for CVE-2018-2668. Network segmentation and access control measures should be implemented to limit exposure of MySQL services to only trusted networks and users, reducing the attack surface. Additionally, monitoring systems should be configured to detect unusual patterns of database service instability or frequent crashes that might indicate exploitation attempts. The vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and represents a significant concern from an ATT&CK perspective under the T1499.004 technique related to network denial of service attacks, demonstrating how database server vulnerabilities can be leveraged for availability impact operations.