CVE-2020-2686 in MySQL Server
Summary
by MITRE
Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Optimizer). Supported versions that are affected are 8.0.18 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 • 03/23/2024
The vulnerability identified as CVE-2020-2686 represents a critical availability threat within Oracle MySQL Server's optimizer component, specifically affecting versions 8.0.18 and earlier. This flaw resides in the server's query optimization logic where a malformed or specially crafted query can trigger unexpected behavior in the database engine's execution path. The vulnerability operates at a fundamental level of the database's core functionality, exploiting how the optimizer processes certain query structures and logical operations that ultimately lead to system instability.
The technical nature of this vulnerability stems from insufficient input validation and error handling within the MySQL Server's query execution engine. When an attacker submits a particular type of query that manipulates the optimizer's internal state or execution flow, the system fails to properly manage the execution context, resulting in a condition that causes the server process to either hang indefinitely or crash repeatedly. This behavior manifests as a denial of service condition that can be triggered through multiple network protocols including TCP/IP connections, making the attack surface particularly broad and accessible.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise the entire database infrastructure's reliability and availability. Attackers with low privilege levels and network access can leverage this weakness to repeatedly crash the MySQL Server, effectively rendering the database service unavailable to legitimate users and applications. The CVSS score of 6.5 reflects the moderate severity of the availability impact, but the cumulative effect of repeated crashes can lead to significant business disruption, data unavailability, and potential financial losses. The vulnerability's ease of exploitation means that even relatively unsophisticated attackers can successfully compromise database availability.
From a cybersecurity perspective, this vulnerability aligns with CWE-121, which describes buffer overflow conditions in memory management, and represents a classic example of how optimization logic can introduce stability risks in database systems. The attack vector follows ATT&CK technique T1499.004 for network denial of service, where adversaries specifically target availability through system instability. Organizations should implement immediate mitigations including applying the latest Oracle security patches, implementing network segmentation to limit access to database servers, and establishing robust monitoring for unusual connection patterns or service disruptions. Additionally, database administrators should consider implementing query validation mechanisms and access controls to limit the potential impact of such attacks. The vulnerability demonstrates the critical importance of thorough testing and validation of database optimization components, as these features often operate at the core of system stability and can introduce cascading failures when not properly secured against malformed inputs.