---
id: "CVE-2026-101789"
kind: "vulnerability"
aliases: ["CVE-2026-101789"]
title: "MySQL Server optimizer flaw lets low-privileged users crash the database"
severity: "medium"
cvss: 6.5
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["databases", "mysql", "package", "self-hosted"]
not_affected_if: ["no-untrusted-db-accounts", "unaffected-version"]
published_at: "2026-10-20T22:18:34+00:00"
first_seen_at: "2026-10-23T21:57:23+00:00"
updated_at: "2026-10-25T03:53:41+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-101789", "first_seen_at": "2026-10-23T21:57:23+00:00"}]
---

# MySQL Server optimizer flaw lets low-privileged users crash the database

A flaw in the MySQL Server optimizer lets an attacker with low-privilege database access trigger a hang or repeatable crash. The result is a denial of service against MySQL Server and MySQL Cluster, with no data read or changed according to the CVSS vector.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Run `SELECT VERSION();` in MySQL and compare against the affected ranges: MySQL Server 8.4.0 to 8.4.12, 9.7.0 to 9.7.3, 26.7.0 to 26.7.1; MySQL Cluster 8.0.0 to 8.0.49, 8.4.0 to 8.4.12, 9.7.0 to 9.7.3, 26.7.0 to 26.7.1.

## Fix

- Upgrade MySQL Server or MySQL Cluster to a release after the affected ranges listed above; the exact fixed version is unknown from the sources.

## Timeline

- 2026-10-23T21:57:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-101789

## From the sources

Vulnerability in the MySQL Server, MySQL Cluster product of Oracle MySQL (component: Server: Optimizer).  Supported versions that are affected are MySQL Server: 8.4.0-8.4.12, 9.7.0-9.7.3, 26.7.0-26.7.1; MySQL Cluster: 8.0.0-8.0.49, 8.4.0-8.4.12, 9.7.0-9.7.3 and  26.7.0-26.7.1. Easily exploitable vulnerability allows low privileged attacker with network access via multiple protocols to compromise MySQL Server, MySQL Cluster.  Successful attacks of this vulnerability can result in unauthorized ability to cause a hang or frequently repeatable crash (complete DOS) of MySQL Server, MySQL Cluster. 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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