CVE-2020-14760 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 5.7.31 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 as well as unauthorized update, insert or delete access to some of MySQL Server accessible data. CVSS 3.1 Base Score 5.5 (Integrity and Availability impacts). CVSS Vector: (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:N/I:L/A:H).
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Analysis
by VulDB Data Team • 11/24/2020
The vulnerability identified as CVE-2020-14760 represents a critical flaw within the MySQL Server optimizer component that affects versions 5.7.31 and earlier. This vulnerability resides in the server's query optimization engine which is responsible for determining the most efficient execution plan for database queries. The flaw manifests when the optimizer processes certain complex query structures that can trigger memory corruption or resource exhaustion conditions. As a high privileged attacker with network access can exploit this weakness, it creates a significant risk to database integrity and availability. The vulnerability's classification as easily exploitable indicates that attackers require minimal technical expertise to leverage this flaw effectively, making it particularly dangerous in production environments where database servers are accessible over networks.
The technical implementation of this vulnerability stems from improper handling of specific query execution paths within the MySQL optimizer module. When processing certain combinations of SQL operations, particularly those involving complex joins, subqueries, or aggregate functions, the optimizer fails to properly validate memory allocations or resource management during query planning. This deficiency can lead to buffer overflows, memory corruption, or excessive resource consumption that ultimately results in system instability. The vulnerability specifically targets the server's ability to maintain consistent query execution states, causing the MySQL service to either hang indefinitely or crash repeatedly. According to the CVSS 3.1 scoring system, this vulnerability carries a base score of 5.5, reflecting moderate severity with impacts to both integrity and availability. The attack vector requires network access with high privileges, suggesting that the exploit likely involves crafting malicious SQL queries that can be executed against the target database server.
The operational impact of CVE-2020-14760 extends beyond simple service disruption to encompass potential data integrity compromise and unauthorized access to sensitive database information. Successful exploitation can result in complete denial of service conditions where the MySQL server becomes unavailable to legitimate users, potentially causing business disruption and data access failures. Additionally, the vulnerability allows for unauthorized modification of database contents through update, insert, or delete operations on accessible data, which can lead to data corruption or information disclosure. This dual impact on availability and integrity makes the vulnerability particularly concerning for organizations relying on MySQL for critical business operations. The complete DOS condition can be achieved through repeated exploitation attempts that cause the server to become unresponsive or crash repeatedly, requiring manual intervention to restore service availability.
Organizations affected by this vulnerability should prioritize immediate remediation through official Oracle patches and updates for MySQL Server versions 5.7.31 and earlier. The recommended mitigation strategy includes implementing network segmentation to limit access to database servers, enforcing strict access controls, and monitoring for unusual query patterns that might indicate exploitation attempts. Security teams should also consider implementing database activity monitoring solutions that can detect anomalous behavior patterns associated with this specific vulnerability. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and may also relate to CWE-787, representing out-of-bounds write vulnerabilities. From an ATT&CK framework perspective, this vulnerability maps to techniques involving privilege escalation and denial of service, specifically targeting the database service layer. Organizations should also implement network-based intrusion detection systems to identify potential exploitation attempts and maintain comprehensive backup and recovery procedures to minimize the impact of service disruption. Regular vulnerability assessments and security audits should be conducted to identify similar weaknesses in database configurations and ensure that all systems remain protected against emerging threats.