CVE-2025-21577: Oracle MySQL Server DoS Vulnerability

CVE-2025-21577 Overview

CVE-2025-21577 is a Denial of Service vulnerability affecting the InnoDB storage engine component of Oracle MySQL Server. 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 instance.

The vulnerability exists in multiple supported versions of MySQL Server and can be exploited via multiple network protocols. Organizations relying on MySQL Server for critical database operations should prioritize remediation to prevent potential service disruptions.

Critical Impact

Successful exploitation can result in complete denial of service of MySQL Server, causing service outages that may affect dependent applications and business operations.

Affected Products

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

Discovery Timeline

• 2025-04-15 - CVE-2025-21577 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2025-21577

Vulnerability Analysis

This vulnerability resides in the InnoDB storage engine component of MySQL Server. InnoDB is the default storage engine for MySQL, handling critical database operations including transaction management, crash recovery, and row-level locking. The flaw allows authenticated attackers to trigger resource exhaustion conditions within the InnoDB component.

The vulnerability is classified under CWE-400 (Uncontrolled Resource Consumption), indicating that the issue stems from improper handling of resource allocation or deallocation within the InnoDB engine. When exploited, this leads to resource exhaustion that causes the MySQL Server to hang or crash repeatedly.

Root Cause

The root cause of CVE-2025-21577 is an uncontrolled resource consumption issue (CWE-400) within the InnoDB storage engine. The vulnerability allows an attacker to manipulate database operations in a way that exhausts system resources, leading to denial of service conditions. The lack of proper resource limits or input validation in specific InnoDB operations enables this exploitation path.

Attack Vector

The attack can be executed remotely over the network through multiple protocols supported by MySQL Server. An attacker requires only low-level privileges (basic database authentication) to exploit this vulnerability. No user interaction is required, making this vulnerability particularly concerning for internet-exposed or internally accessible MySQL Server deployments.

The attack flow involves:

1. Establishing a network connection to the MySQL Server
2. Authenticating with low-privilege credentials
3. Executing specific operations that trigger the resource exhaustion condition in InnoDB
4. The server becomes unresponsive or crashes, denying service to legitimate users

Since no verified code examples are available for this vulnerability, organizations should consult the Oracle Security Alert April 2025 for detailed technical information about the exploitation mechanism.

Detection Methods for CVE-2025-21577

Indicators of Compromise

• Unexpected MySQL Server crashes or hangs without apparent system resource limitations
• Repeated crash-recovery cycles in MySQL error logs related to InnoDB operations
• Abnormal database connection patterns from low-privileged accounts
• Unusual resource consumption spikes in MySQL processes before service interruption

Detection Strategies

• Monitor MySQL error logs for InnoDB-related crash dumps and recovery messages
• Implement alerting for MySQL Server process restarts and unexpected terminations
• Track database connection attempts and query patterns from authenticated users
• Deploy network monitoring to identify unusual traffic patterns to MySQL ports (3306/tcp)

Monitoring Recommendations

• Enable MySQL Server performance monitoring to detect resource exhaustion conditions
• Configure automated alerts for MySQL service availability and response times
• Implement database activity monitoring to log and analyze all InnoDB operations
• Review authentication logs regularly to identify potential malicious account usage

How to Mitigate CVE-2025-21577

Immediate Actions Required

• Apply the security patches provided in Oracle's Critical Patch Update for April 2025
• Review and restrict database user privileges to the minimum necessary
• Implement network segmentation to limit access to MySQL Server from untrusted sources
• Enable MySQL Server audit logging to track suspicious activities

Patch Information

Oracle has released security patches to address this vulnerability as part of the April 2025 Critical Patch Update. Affected organizations should upgrade to the following 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, refer to the Oracle Security Alert April 2025. Additional vendor information is available in the NetApp Security Advisory NTAP-20250502-0006.

Workarounds

• Restrict network access to MySQL Server to trusted hosts only using firewall rules
• Review and revoke unnecessary database user accounts and privileges
• Implement connection limits and rate limiting for database connections
• Consider deploying MySQL behind a database proxy or load balancer with connection management capabilities

# Example: Restrict MySQL network access using firewall rules
# Allow MySQL connections only from trusted application servers
iptables -A INPUT -p tcp --dport 3306 -s 10.0.1.0/24 -j ACCEPT
iptables -A INPUT -p tcp --dport 3306 -j DROP

# Review MySQL user privileges
mysql -u root -p -e "SELECT user, host, authentication_string FROM mysql.user;"

# Revoke unnecessary privileges from users
# mysql -u root -p -e "REVOKE ALL PRIVILEGES ON *.* FROM 'username'@'host';"