CVE-2018-2780 in MySQL Server
Summary
by MITRE
Vulnerability in the MySQL Server component of Oracle MySQL (subcomponent: Server: Optimizer). Supported versions that are affected are 5.7.21 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 • 03/02/2023
The vulnerability identified as CVE-2018-2780 resides within the MySQL Server component, specifically within the Server: Optimizer subcomponent, affecting MySQL versions 5.7.21 and earlier. This represents a critical availability risk that demonstrates how optimization routines within database systems can become attack vectors when not properly secured. The vulnerability's classification as easily exploitable indicates that attackers with minimal privileges and network access can leverage this flaw to compromise database server operations. The CVSS 3.0 scoring system assigns a base score of 6.5, reflecting the high availability impact that can result from successful exploitation, with the vector AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H indicating network-based access with low complexity, requiring only low privileges, no user interaction, and resulting in high availability impact. This vulnerability operates at the intersection of database optimization and security, where the very mechanisms designed to improve performance become potential attack surfaces.
The technical flaw manifests in the optimizer's handling of specific query execution paths that can trigger memory corruption or resource exhaustion conditions. When the optimizer processes certain complex queries or joins, it can enter into problematic execution flows that lead to server instability. This typically occurs during query planning phases where the optimizer attempts to determine the most efficient execution strategy, particularly when dealing with complex nested queries or large datasets. The vulnerability exploits weaknesses in the memory management and execution path validation within the optimizer module, allowing an attacker to craft specific queries that will cause the MySQL server process to either hang indefinitely or crash repeatedly. The nature of this flaw means that even legitimate database operations could potentially trigger the vulnerability if they involve the specific query patterns that expose the optimizer bug.
The operational impact of CVE-2018-2780 extends beyond simple service disruption to encompass complete denial of service conditions that can severely impact business operations. Organizations relying on MySQL databases for critical applications face the risk of extended downtime when this vulnerability is exploited, potentially affecting customer-facing applications, transaction processing systems, and data availability for business operations. The vulnerability's ability to cause either hangs or frequent crashes means that database administrators must contend with unpredictable service interruptions that can last from minutes to hours depending on the exploitation method. This disruption can cascade through dependent systems, affecting application availability, user experience, and overall business continuity. The low privilege requirement means that even unprivileged users with network access can potentially exploit this vulnerability, making it particularly concerning for environments where database access is not strictly controlled. The vulnerability essentially allows attackers to consume server resources or trigger execution paths that lead to process termination or resource exhaustion, creating a persistent threat to database availability.
Mitigation strategies for CVE-2018-2780 focus primarily on immediate version upgrades to MySQL 5.7.22 or later, which contain patches addressing the optimizer vulnerability. Organizations should implement network segmentation and access controls to limit exposure of MySQL servers to untrusted networks, reducing the attack surface available to potential exploiters. Database administrators should also consider implementing query monitoring and restriction mechanisms to identify and block potentially malicious query patterns that could trigger the optimizer bug. The vulnerability's classification under CWE-129 (Improper Validation of Array Index) and its alignment with ATT&CK technique T1499.004 (Endpoint Denial of Service) indicates that defensive measures should include both application-level monitoring and network-level controls. Additionally, organizations should conduct thorough testing of upgraded systems to ensure that the patch does not introduce compatibility issues with existing database applications, as the optimizer changes may affect query execution plans and performance characteristics. Regular security assessments and vulnerability scanning should be implemented to identify other potential vulnerabilities in database systems, as this incident demonstrates how optimization components can become security risks when not properly validated.