---
id: "CVE-2026-101766"
kind: "vulnerability"
aliases: ["CVE-2026-101766"]
title: "MySQL Server replication flaw lets a privileged user crash the server"
severity: "medium"
cvss: 4.4
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["database-admins", "mysql", "package", "self-hosted"]
not_affected_if: ["managed-hosting", "version-outside-range"]
published_at: "2026-10-20T22:18:31+00:00"
first_seen_at: "2026-10-23T21:57:23+00:00"
updated_at: "2026-10-25T04:37:00+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-101766", "first_seen_at": "2026-10-23T21:57:23+00:00"}]
---

# MySQL Server replication flaw lets a privileged user crash the server

A flaw in the MySQL Server and MySQL Cluster replication component lets a highly privileged attacker over the network hang or repeatedly crash the database. The sources describe only an availability impact, with no data read or changed.

_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 8.4.0-8.4.12, 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, 26.7.0-26.7.1
- Check whether replication is in use on the instance with `SHOW REPLICA STATUS;` or `SHOW REPLICAS;`

## Fix

- Move MySQL Server or MySQL Cluster to a release outside the affected ranges, as published in Oracle's Critical Patch Update for the relevant product line
- unknown for the exact fixed version numbers, as the sources do not list them

## Timeline

- 2026-10-23T21:57:23+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-101766

## From the sources

Vulnerability in the MySQL Server, MySQL Cluster product of Oracle MySQL (component: Server: Replication).  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. Difficult to exploit vulnerability allows high 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 4.4 (Availability impacts).  CVSS Vector: (CVSS:3.1/AV:N/AC:H/PR:H/UI:N/S:U/C:N/I:N/A:H).

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_