CVE-2023-21946 in MySQL Server
Summary
by MITRE • 04/18/2023
Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Optimizer). Supported versions that are affected are 8.0.32 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 • 05/08/2025
The vulnerability identified as CVE-2023-21946 resides within the MySQL Server component known as the Server: Optimizer, affecting Oracle MySQL versions 8.0.32 and earlier. This represents a significant security concern as it operates within the core database engine's query optimization functionality, which is fundamental to how MySQL processes and executes database operations. The vulnerability's classification as easily exploitable indicates that attackers with minimal privileges and network access can leverage this flaw to compromise database server integrity. The affected version range suggests this issue has been present in recent MySQL releases, making it particularly concerning for organizations running these versions in production environments.
The technical nature of this vulnerability manifests as a flaw in the optimizer component that can be triggered through multiple network protocols, providing attackers with various attack vectors to exploit the system. The CVSS 3.1 scoring system assigns this vulnerability a base score of 6.5, which falls into the medium severity category, though the availability impact component receives a high rating of eight, indicating the potential for complete denial of service. The attack vector AV:N indicates network-based exploitation is possible, while AC:L shows low attack complexity, making it accessible to a wide range of threat actors. The PR:L designation reveals that only low privileged access is required, significantly broadening the attack surface as even users with minimal database permissions could potentially exploit this weakness.
The operational impact of successfully exploiting CVE-2023-21946 can be severe for database-dependent applications and services. An attacker who successfully triggers this vulnerability can cause the MySQL server to hang or experience frequently repeatable crashes, effectively creating a complete denial of service condition that can render database services unavailable to legitimate users. This type of disruption can have cascading effects throughout enterprise applications that rely on MySQL for data persistence, potentially causing widespread system outages and business disruption. The vulnerability's ability to cause repeated crashes suggests that even a single successful exploitation attempt could potentially maintain ongoing service disruption until the server is manually restarted or the underlying issue is resolved through patching.
Organizations should prioritize immediate remediation of this vulnerability through the application of Oracle's security patches, which would address the specific flaw in the optimizer component. The mitigation strategy should include comprehensive testing of patches in non-production environments before deployment to ensure compatibility with existing database applications. Network segmentation and access controls should be reviewed to limit unnecessary network access to MySQL servers, particularly for non-essential users or applications. Monitoring systems should be enhanced to detect unusual patterns of database server instability or repeated connection failures that might indicate exploitation attempts. This vulnerability aligns with CWE-119 which describes weaknesses in memory management, and potentially relates to ATT&CK technique T1499 which covers network disruption attacks targeting availability. Organizations should also consider implementing database activity monitoring solutions that can detect anomalous behavior patterns consistent with optimizer-based attacks, providing additional layers of defense beyond traditional patch management approaches.