CVE-2020-14769 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 5.6.49 and prior, 5.7.31 and prior and 8.0.21 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 3.1 Base Score 6.5 (Availability impacts). CVSS Vector: (CVSS:3.1/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 • 11/24/2020
The vulnerability identified as CVE-2020-14769 resides within the MySQL Server optimizer component of Oracle MySQL, representing a significant availability risk that affects multiple version streams including 5.6.49 and earlier, 5.7.31 and earlier, and 8.0.21 and earlier. This flaw operates at the core of MySQL's query processing capabilities where the optimizer component is responsible for determining the most efficient execution plan for database queries. The vulnerability's classification as easily exploitable indicates that attackers with minimal privileges and network access can leverage this weakness to compromise system availability. The attack vector requires only network connectivity through multiple protocols, making it particularly dangerous in environments where database servers are accessible over networks. This vulnerability falls under the Common Weakness Enumeration category CWE-476 which describes a null pointer dereference, a condition where a program attempts to access memory through a null pointer, leading to system instability and potential crashes.
The technical exploitation of this vulnerability occurs when specific query patterns trigger an improper handling within the optimizer's execution path, causing the MySQL server process to enter a state where it becomes unresponsive or crashes repeatedly. This behavior manifests as a denial of service condition that can be either temporary or persistent depending on the attack methodology and system configuration. The CVSS 3.1 scoring of 6.5 reflects the moderate to high severity impact on system availability, with the attack complexity rated as low and the privilege requirement as low, indicating that even unauthorized users with basic network access can potentially trigger the vulnerability. The availability impact is rated as high (A:H) because successful exploitation results in complete denial of service, effectively preventing legitimate database access and operations. The vulnerability's impact extends beyond simple service disruption as it can cause cascading failures in applications that depend on database connectivity, potentially affecting business operations and data availability.
The operational impact of CVE-2020-14769 extends significantly beyond immediate system crashes, as it can disrupt database operations across entire enterprise environments. Organizations running affected MySQL versions face the risk of extended downtime, potential data loss during crash recovery, and compromised service level agreements with customers. The vulnerability's ability to cause repeated crashes means that even brief exploitation attempts can result in prolonged system unavailability, requiring manual intervention for recovery and system restart. This type of vulnerability is particularly concerning in production environments where database uptime is critical for business operations, and can be exploited as part of broader attack campaigns targeting database infrastructure. The attack surface is amplified by the fact that multiple protocols can be used to reach the vulnerable server, increasing the likelihood of successful exploitation through various network entry points and potentially bypassing traditional network segmentation controls.
Mitigation strategies for CVE-2020-14769 should prioritize immediate patching of affected MySQL server installations to the latest supported versions that contain the relevant security fixes. Organizations should implement network segmentation controls to limit access to database servers, restricting connections to only trusted sources and implementing proper authentication mechanisms to reduce the attack surface. Monitoring systems should be enhanced to detect unusual patterns of database connection attempts or query execution that could indicate exploitation attempts. Additionally, implementing database firewalls and query filtering mechanisms can help prevent exploitation by blocking malicious query patterns that trigger the vulnerability. The remediation process should also include comprehensive testing of patched systems to ensure that the vulnerability has been properly addressed without introducing new compatibility issues. Organizations should consider implementing automated patch management solutions to ensure timely deployment of security updates across all database infrastructure components. Security teams should also conduct regular vulnerability assessments and penetration testing to identify and address similar weaknesses in database configurations and access controls. The ATT&CK framework categorizes this vulnerability under the T1499.004 technique for network denial of service attacks, emphasizing the importance of implementing robust network security controls and monitoring to detect and prevent such exploitation attempts.