CVE-2026-21998: Medium severity Oracle MySQL Server vulnerability
Vulnerability in the MySQL Server product of Oracle MySQL (component: Server: Optimizer). Supported versions that are affected are 8.0.0-8.0.45, 8.4.0-8.4.8 and 9.0.0-9.6.0. 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).
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Compensating control
Restrict network exposure of MySQL Server. Use firewall/ACL rules, network segmentation, or a WAF to allow MySQL access only from trusted hosts and management networks; block or limit access from untrusted networks and the public internet.
- Operational
Implement availability monitoring and incident response for MySQL Server to detect hangs or frequent crashes (DoS). Configure alerts, automated restart procedures where appropriate, and be prepared to apply vendor-supplied patches or mitigations when they are released.
Event History
Frequently Asked Questions
What is the severity of CVE-2026-21998?
CVE-2026-21998 is classified as an easily exploitable vulnerability with high potential impact.
How do I fix CVE-2026-21998?
To fix CVE-2026-21998, upgrade your MySQL Server to a version beyond 8.0.45, 8.4.8, or 9.6.0.
What components of MySQL Server are affected by CVE-2026-21998?
CVE-2026-21998 affects the Optimizer component of Oracle MySQL Server.
What versions of Oracle MySQL are impacted by CVE-2026-21998?
The impacted versions of Oracle MySQL are 8.0.0 to 8.0.45, 8.4.0 to 8.4.8, and 9.0.0 to 9.6.0.
Who can exploit CVE-2026-21998?
CVE-2026-21998 can be exploited by a high privileged attacker with network access through multiple protocols.