CVE-2020-14837 in MySQL Server
Summary
by MITRE • 10/21/2020
Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Optimizer). Supported versions that are affected are 8.0.21 and prior. Easily exploitable vulnerability allows high 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 3.1 Base Score 4.9 (Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H).
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Analysis
by VulDB Data Team • 11/24/2020
The vulnerability identified as CVE-2020-14837 resides within the MySQL Server optimizer component of Oracle MySQL, specifically affecting versions 8.0.21 and earlier. This represents a critical availability-focused weakness that demonstrates how seemingly routine database operations can be exploited to cause significant service disruption. The vulnerability operates at the core of MySQL's query processing capabilities, where the optimizer is responsible for determining the most efficient execution plan for database queries. When exploited, this flaw allows an attacker with high privileges and network access to manipulate the server's behavior in a manner that can lead to complete system unavailability.
The technical nature of this vulnerability stems from improper handling within the server's optimizer module, which processes and executes database queries. Attackers with elevated privileges can craft specific queries or conditions that trigger a pathological behavior in the optimizer's code path, leading to resource exhaustion or internal state corruption. The vulnerability's exploitability is classified as easily accessible due to the requirement of only high privileged access and network connectivity through multiple protocols, making it particularly dangerous in environments where administrative accounts might be compromised or where insufficient privilege separation exists. This characteristic aligns with CWE-248, which addresses "Uncaught Exception" conditions that can lead to system instability and denial of service scenarios.
The operational impact of successfully exploiting CVE-2020-14837 can be devastating for database-dependent applications and services. The vulnerability can result in complete denial of service conditions where the MySQL server becomes unresponsive or crashes repeatedly, requiring manual intervention for recovery. This disruption affects all database operations and can cascade through applications that depend on the database, potentially causing widespread service outages across an organization's infrastructure. The CVSS score of 4.9 reflects the availability impact severity, indicating that while the attack requires elevated privileges, the consequences are severe enough to warrant immediate attention. Organizations implementing the ATT&CK framework would categorize this as a system service disruption technique, potentially leading to broader impact through data availability and business continuity concerns.
Mitigation strategies for this vulnerability should focus on immediate patching of affected MySQL Server instances to version 8.0.22 or later, which contains the necessary fixes for the optimizer flaw. Network segmentation and privilege minimization should be enforced to reduce the attack surface, ensuring that only necessary administrative accounts have high privileges. Additionally, implementing monitoring solutions that can detect unusual query patterns or server behavior that might indicate exploitation attempts can provide early warning capabilities. Organizations should also consider implementing database activity monitoring and anomaly detection systems to identify potential exploitation attempts before they can cause significant damage. The vulnerability's classification under the availability impact category emphasizes the importance of robust backup and recovery procedures, as well as redundant database systems that can maintain service continuity during incident response activities.