# CVE-2026-101784: Oracle MySQL Server denial of service in Optimizer

Source: https://junglewise.ai/threats/cve-2026-101784-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-2026-101784 · Severity: medium · CVSS 4.9 · Published 2026-10-20

A vulnerability in Oracle MySQL Server and MySQL Cluster's query optimizer component allows a privileged attacker to crash the database via network access. Successful exploitation causes a complete denial of service, disrupting database availability and business operations dependent on the database.

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-2026-101784 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-101784 being exploited in the wild.

**How severe is CVE-2026-101784?** 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-2026-101784?** 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-2026-101784 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-101784?** 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

A denial-of-service vulnerability in the Server: Optimizer component allows a high-privileged attacker with network access to trigger a hang or crash of MySQL Server or MySQL Cluster. The vulnerability requires high privilege level and can be exploited via multiple protocols, resulting in unavailability of the database service.

## 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)