CVE-2026-60186: MySQL Server DoS Vulnerability

CVE-2026-60186 Overview

CVE-2026-60186 affects the Group Replication Plugin component in Oracle MySQL Server and MySQL Cluster. A high-privileged attacker with network access can trigger a hang or repeatable crash, resulting in complete denial of service. The flaw is classified under CWE-400 (Uncontrolled Resource Consumption) and impacts availability only. Oracle disclosed the issue in the July 2026 Critical Patch Update.

Critical Impact

Successful exploitation causes a hang or frequently repeatable crash of MySQL Server or MySQL Cluster, producing a complete denial of service for database workloads relying on Group Replication.

Affected Products

• MySQL Server versions 8.4.0 through 8.4.10 and 9.7.0 through 9.7.1
• MySQL Cluster versions 8.0.0 through 8.0.47
• MySQL Cluster versions 8.4.0 through 8.4.10 and 9.7.0 through 9.7.1

Discovery Timeline

• 2026-07-21 - CVE-2026-60186 published to the National Vulnerability Database
• 2026-07-23 - CVE-2026-60186 last modified in NVD

Technical Details for CVE-2026-60186

Vulnerability Analysis

The vulnerability resides in the Server: Group Replication Plugin, which coordinates state and transactions across replicated MySQL nodes. An attacker who already holds high privileges on the database can send crafted requests over network protocols supported by the server. Processing these requests causes the server to hang or crash repeatedly, halting all client operations.

The impact is limited to availability. Confidentiality and integrity are not affected because the flaw does not permit data access or modification. However, the crash is described as frequently repeatable, meaning an attacker can hold the database offline for as long as they retain access.

Exploitation is rated as difficult because it requires elevated privileges and specific conditions during Group Replication processing. Environments that expose replication endpoints to broader networks face increased exposure.

Root Cause

The root cause is uncontrolled resource consumption inside the Group Replication Plugin (CWE-400). The plugin fails to bound resources or handle specific message sequences safely, allowing an attacker to induce a fatal condition in the server process.

Attack Vector

The attack originates from the network and can use multiple MySQL protocols. The attacker must already possess high privileges on the target instance. No user interaction is required, and the scope remains unchanged. See the Oracle Security Alert - July 2026 for vendor technical details.

No public proof-of-concept code is available for CVE-2026-60186 at this time. The EPSS score is 0.336% as of 2026-07-23, indicating a low observed likelihood of exploitation in the short term.

Detection Methods for CVE-2026-60186

Indicators of Compromise

• Unexpected MySQL Server or MySQL Cluster process crashes with core dumps referencing the Group Replication Plugin
• Repeated node ejections or view change events in Group Replication logs without corresponding operational changes
• Sudden loss of quorum across replication group members following privileged client sessions

Detection Strategies

• Monitor MySQL error logs for recurring plugin faults, assertion failures, or abnormal shutdowns tied to group_replication subsystems
• Correlate authenticated administrative sessions with subsequent instability events across replication group members
• Alert on process restarts of mysqld occurring in close succession across multiple nodes

Monitoring Recommendations

• Enable verbose logging for the Group Replication Plugin and forward logs to a centralized analytics platform for correlation
• Track availability metrics (uptime, replication lag, member state transitions) with thresholds that surface repeated crashes
• Review privileged account activity for anomalous connections from unexpected source hosts or network segments

How to Mitigate CVE-2026-60186

Immediate Actions Required

• Apply the fixes from the Oracle Critical Patch Update - July 2026 to all affected MySQL Server and MySQL Cluster instances
• Inventory MySQL deployments to identify versions 8.0.0-8.0.47, 8.4.0-8.4.10, and 9.7.0-9.7.1 that require patching
• Rotate credentials for high-privilege database accounts if abuse is suspected

Patch Information

Oracle addressed CVE-2026-60186 in the July 2026 Critical Patch Update. Administrators should upgrade MySQL Server and MySQL Cluster to the fixed versions listed in the advisory. Test the patch in a staging environment before rolling out to production replication groups to avoid disrupting quorum.

Workarounds

• Restrict network access to MySQL replication ports using firewalls, security groups, or private network segmentation
• Limit accounts holding replication and administrative privileges, and enforce strong authentication for those accounts
• Isolate Group Replication traffic on a dedicated management network separate from general application traffic

# Example: restrict access to the default MySQL port to trusted replication peers only
iptables -A INPUT -p tcp --dport 3306 -s 10.0.0.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 3306 -j DROP

# Revoke unnecessary replication privileges
mysql -u root -p -e "REVOKE GROUP_REPLICATION_ADMIN ON *.* FROM 'appuser'@'%';"