# CVE-2026-101798: Oracle MySQL Server Optimizer denial of service

Source: https://junglewise.ai/threats/cve-2026-101798-vulnerability-in-the-mysql-server-mysql-cluster-product-of  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-20. Updated: 2026-10-20  
License: CC BY 4.0 with a link back

CVE-2026-101798 · Severity: medium · CVSS 4.9 · Published 2026-10-20

A flaw in MySQL Server and MySQL Cluster's query optimizer component allows privileged database users to crash the database engine via malformed queries, causing complete service unavailability. An attacker with administrative privileges could disrupt business-critical database operations by triggering the vulnerability over the network.

Technologies: [Oracle MySQL Server](https://junglewise.ai/threats/technologies/mysql-server), [Oracle Mysql Cluster](https://junglewise.ai/threats/technologies/mysql-cluster). Vendors: [Oracle](https://junglewise.ai/threats/vendors/oracle).

## Quick answers

**Is CVE-2026-101798 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-101798 being exploited in the wild.

**How severe is CVE-2026-101798?** Medium severity, with a CVSS score of 4.9, published 20 October 2026.

**Which products and versions are affected?** Oracle MySQL Server 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1; Oracle Mysql Cluster 8.0.0-8.0.49, 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1.

**Is there a fix for CVE-2026-101798?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-101798 attacked?** It is attacked over the network, in a hosted service.

**Am I affected by CVE-2026-101798?** Check whether you run Oracle MySQL Server or Oracle Mysql Cluster at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Technical details

The Server: Optimizer component in MySQL contains an exploitable flaw that permits high-privileged attackers to trigger a denial of service condition via multiple protocols. Successful exploitation results in hangs or repeatable crashes of the database. The vulnerability requires prior authentication with high privileges and network access, but no additional user interaction.

## Affected products

- Oracle MySQL Server 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1
- Oracle MySQL Cluster 8.0.0-8.0.49, 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1

## Timeline

- 2026-10-20: disclosed

## References

- [https://www.oracle.com/security-alerts/cpuoct2026.html](https://www.oracle.com/security-alerts/cpuoct2026.html)

## Related threats

- [Oracle MySQL Server XML parsing privilege escalation](https://junglewise.ai/threats/cve-2026-101803-vulnerability-in-the-mysql-server-mysql-cluster-product-of)
- [Oracle MySQL Server parser denial of service](https://junglewise.ai/threats/cve-2026-101802-vulnerability-in-the-mysql-server-mysql-cluster-product-of)
- [Oracle MySQL Server Optimizer denial of service](https://junglewise.ai/threats/cve-2026-101801-vulnerability-in-the-mysql-server-mysql-cluster-product-of)
- [Oracle MySQL Server privilege escalation in Security: Privileges](https://junglewise.ai/threats/cve-2026-101800-vulnerability-in-the-mysql-server-mysql-cluster-product-of)
- [Oracle MySQL Server denial of service in Group Replication](https://junglewise.ai/threats/cve-2026-101799-vulnerability-in-the-mysql-server-mysql-cluster-product-of)