CVE-2025-21505: Oracle MySQL Server DoS Vulnerability

CVE-2025-21505 Overview

CVE-2025-21505 is a Denial of Service (DoS) vulnerability in the MySQL Server product of Oracle MySQL, specifically affecting the Server: Components Services component. This vulnerability allows a high-privileged attacker with network access to cause a complete denial of service by triggering a hang or frequently repeatable crash of the MySQL Server.

Critical Impact

Successful exploitation allows attackers to cause complete unavailability of MySQL Server through repeatable crashes, potentially disrupting critical database operations and dependent applications.

Affected Products

• Oracle MySQL Server versions 8.0.40 and prior
• Oracle MySQL Server versions 8.4.3 and prior
• Oracle MySQL Server versions 9.1.0 and prior

Discovery Timeline

• 2025-01-21 - CVE-2025-21505 published to NVD
• 2025-11-03 - Last updated in NVD database

Technical Details for CVE-2025-21505

Vulnerability Analysis

This vulnerability resides within the Server: Components Services component of Oracle MySQL Server. The flaw is classified under CWE-770 (Allocation of Resources Without Limits or Throttling), indicating that the vulnerable component fails to properly manage resource allocation, enabling an attacker to exhaust server resources and trigger a denial of service condition.

The attack is network-based and requires high privileges to execute, meaning the attacker must have administrative or elevated access to the MySQL Server. However, the ease of exploitation is notable—once an attacker has the required privileges and network access, the vulnerability can be easily triggered via multiple protocols supported by MySQL Server.

Root Cause

The root cause stems from improper resource allocation handling within the Components Services module. CWE-770 vulnerabilities occur when software does not properly limit or throttle resource consumption, allowing attackers to force excessive allocation that can lead to resource exhaustion. In this case, the MySQL Server fails to implement adequate safeguards against resource exhaustion attacks, enabling a privileged user to cause repeated server crashes or hangs.

Attack Vector

The attack vector is network-based, requiring the attacker to have high-privilege access to the MySQL Server. The exploitation path involves:

1. The attacker establishes a network connection to the vulnerable MySQL Server instance
2. Using administrative privileges, the attacker sends crafted requests to the Components Services component
3. These requests trigger improper resource handling within the server
4. The server either hangs or crashes, resulting in complete unavailability
5. The attack can be repeated to maintain the denial of service condition

The vulnerability does not impact confidentiality or integrity—only availability is affected. However, the impact to availability is considered high, as successful exploitation results in complete service disruption.

Detection Methods for CVE-2025-21505

Indicators of Compromise

• Unexpected MySQL Server crashes or hangs without apparent cause
• Unusual resource consumption patterns (memory, CPU) by MySQL Server processes
• Repeated service restarts in MySQL error logs
• Anomalous administrative connections from unexpected sources

Detection Strategies

• Monitor MySQL error logs for crash reports and unexpected restarts related to Components Services
• Implement database activity monitoring (DAM) to track privileged user actions
• Configure alerting for unusual administrative connection patterns
• Deploy network-based intrusion detection to identify anomalous MySQL protocol traffic

Monitoring Recommendations

• Enable MySQL audit logging to capture all administrative actions
• Set up automated alerts for MySQL service availability monitoring
• Implement connection rate limiting and monitoring for administrative accounts
• Review privileged account access logs regularly for suspicious activity

How to Mitigate CVE-2025-21505

Immediate Actions Required

• Apply the Oracle Critical Patch Update (January 2025) to all affected MySQL Server instances
• Review and restrict high-privilege account access to only necessary personnel
• Implement network segmentation to limit MySQL Server exposure
• Enable enhanced logging to detect potential exploitation attempts

Patch Information

Oracle has addressed this vulnerability in their January 2025 Critical Patch Update. Organizations should apply the appropriate patch based on their MySQL Server version:

• MySQL Server 8.0.x: Upgrade to version 8.0.41 or later
• MySQL Server 8.4.x: Upgrade to version 8.4.4 or later
• MySQL Server 9.1.x: Upgrade to version 9.1.1 or later

For detailed patch information, refer to the Oracle Critical Patch Update Advisory. NetApp customers should also review the NetApp Security Advisory NTAP-20250131-0004 for additional guidance.

Workarounds

• Restrict network access to MySQL Server by implementing firewall rules limiting connections to trusted IP addresses
• Review and minimize the number of accounts with high privileges on MySQL Server
• Implement connection limits per user to reduce the impact of potential abuse
• Consider deploying MySQL Proxy or connection pooling to add an additional layer of access control

# Example: Restrict MySQL network access via firewall
# 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 high-privilege accounts in MySQL
mysql -e "SELECT user, host FROM mysql.user WHERE Super_priv='Y';"