CVE-2025-30687: Oracle MySQL Server DoS Vulnerability

CVE-2025-30687 Overview

CVE-2025-30687 is a Denial of Service (DoS) vulnerability in the MySQL Server product of Oracle MySQL, specifically affecting the Server: Optimizer component. This vulnerability allows a low-privileged attacker with network access to cause a complete denial of service condition, resulting in a hang or frequently repeatable crash of the MySQL Server.

Critical Impact

Successful exploitation enables attackers to completely disrupt MySQL Server availability, causing service outages that can affect dependent applications and business operations.

Affected Products

• Oracle MySQL Server 8.0.0 through 8.0.41
• Oracle MySQL Server 8.4.0 through 8.4.4
• Oracle MySQL Server 9.0.0 through 9.2.0

Discovery Timeline

• 2025-04-15 - CVE-2025-30687 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2025-30687

Vulnerability Analysis

This vulnerability resides in the Server: Optimizer component of Oracle MySQL Server. The Optimizer is a critical component responsible for determining the most efficient execution plan for SQL queries. A flaw in this component allows attackers to craft malicious queries that trigger resource exhaustion or improper handling, leading to server instability.

The vulnerability is classified under CWE-732 (Incorrect Permission Assignment for Critical Resource), suggesting that the underlying issue relates to improper permission handling that can be exploited to cause denial of service conditions. The attack can be executed remotely over the network using multiple protocols, making it accessible to any authenticated user with low-level privileges.

Root Cause

The root cause stems from improper resource management within the MySQL Optimizer component. When processing certain types of queries, the optimizer fails to properly validate or limit resource consumption, allowing a malicious actor to trigger conditions that result in server hangs or crashes. The CWE-732 classification indicates that permission controls may not adequately restrict access to critical server resources during query optimization.

Attack Vector

The attack is network-based and requires only low-level authentication privileges. An attacker who has valid credentials to connect to the MySQL server can exploit this vulnerability by submitting specially crafted queries that trigger the flaw in the Optimizer component. No user interaction is required beyond the attacker's initial connection and query submission.

The vulnerability affects availability exclusively—there is no impact on data confidentiality or integrity. However, the ability to cause complete server crashes or hangs represents a significant operational risk, particularly for production database environments.

Detection Methods for CVE-2025-30687

Indicators of Compromise

• Unexpected MySQL Server crashes or service restarts without apparent cause
• Elevated query processing times in the optimizer component
• Repeated connection attempts from the same user followed by server instability
• Unusual patterns of complex or malformed queries in MySQL logs

Detection Strategies

• Monitor MySQL error logs for optimizer-related crashes or hangs
• Implement query analysis to detect anomalous or malicious query patterns
• Configure alerting for MySQL service availability and unexpected restarts
• Track authentication events correlated with server instability incidents

Monitoring Recommendations

• Enable MySQL slow query logging to identify potentially malicious queries targeting the optimizer
• Deploy network-level monitoring to detect unusual database traffic patterns
• Implement database activity monitoring (DAM) solutions to track query execution
• Configure health checks and automated alerting for MySQL service availability

How to Mitigate CVE-2025-30687

Immediate Actions Required

• Apply the Oracle Critical Patch Update (CPU) for April 2025 immediately
• Review and restrict database user privileges to minimum required levels
• Implement network segmentation to limit access to MySQL servers
• Enable query timeout limits to prevent long-running malicious queries

Patch Information

Oracle has released patches for this vulnerability as part of the April 2025 Critical Patch Update. Administrators should upgrade to patched versions:

• MySQL Server 8.0.42 or later for the 8.0.x branch
• MySQL Server 8.4.5 or later for the 8.4.x branch
• MySQL Server 9.2.1 or later for the 9.x branch

For detailed patch information and download links, refer to the Oracle Critical Patch Update April 2025. Additional vendor guidance is available in the NetApp Security Advisory NTAP-20250502-0006.

Workarounds

• Restrict network access to MySQL servers using firewall rules to trusted IP addresses only
• Implement query timeout settings using max_execution_time to limit resource consumption
• Review and audit user privileges, removing unnecessary access rights
• Consider deploying a database firewall or proxy that can filter potentially malicious queries

# Configuration example - MySQL query timeout and connection limits
# Add to my.cnf or my.ini configuration file

[mysqld]
# Set maximum query execution time in milliseconds (e.g., 30 seconds)
max_execution_time=30000

# Limit maximum connections per user
max_user_connections=50

# Enable slow query log for monitoring
slow_query_log=1
slow_query_log_file=/var/log/mysql/slow-query.log
long_query_time=10