CVE-2025-21534 Overview
CVE-2025-21534 is a Denial of Service vulnerability affecting the MySQL Server product of Oracle MySQL, specifically in the Server: Performance Schema component. This vulnerability allows a high-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 with administrative privileges to completely disrupt MySQL Server availability through repeatable crashes, potentially causing significant service outages for dependent applications.
Affected Products
- Oracle MySQL Server 8.0.39 and prior versions
- Oracle MySQL Server 8.4.2 and prior versions
- Oracle MySQL Server 9.0.1 and prior versions
Discovery Timeline
- 2025-01-21 - CVE-2025-21534 published to NVD
- 2025-11-03 - Last updated in NVD database
Technical Details for CVE-2025-21534
Vulnerability Analysis
This vulnerability resides in the Performance Schema component of Oracle MySQL Server. The Performance Schema is a feature designed for monitoring MySQL Server execution at a low level, providing detailed performance metrics and event information. The flaw enables an authenticated attacker with high privileges to trigger resource allocation without appropriate limits (CWE-770), leading to a denial of service condition.
The vulnerability is easily exploitable, requiring no user interaction once the attacker has established network access with appropriate credentials. The impact is isolated to availability, with no effect on confidentiality or integrity of the data stored within the MySQL Server.
Root Cause
The root cause is classified as CWE-770: Allocation of Resources Without Limits or Throttling. The Performance Schema component fails to properly manage resource allocation, allowing a privileged user to consume server resources in a manner that triggers a crash or hang condition. This lack of proper resource limiting enables the denial of service attack vector.
Attack Vector
The attack vector is network-based, allowing exploitation via multiple protocols supported by MySQL Server. The attacker must possess high-level privileges (such as administrative access) to the MySQL Server instance. Once authenticated, the attacker can manipulate Performance Schema operations in a way that exhausts resources or triggers a crash condition.
The attack does not require user interaction and has low complexity, making it straightforward to execute once the prerequisite access is obtained. The scope is unchanged, meaning the vulnerability only affects the MySQL Server itself without impacting other components in the hosting environment.
Detection Methods for CVE-2025-21534
Indicators of Compromise
- Unexpected MySQL Server crashes or hangs, particularly when Performance Schema operations are being performed
- Abnormal resource consumption patterns in MySQL Server processes
- Repeated database service restarts without apparent cause
- Error logs indicating Performance Schema-related failures or resource exhaustion
Detection Strategies
- Monitor MySQL Server error logs for crash reports and unusual Performance Schema errors
- Implement database activity monitoring to detect anomalous queries from high-privileged accounts
- Deploy network monitoring to identify unusual connection patterns to MySQL Server ports
- Configure alerting for unexpected MySQL service restarts or availability issues
Monitoring Recommendations
- Enable comprehensive MySQL Server audit logging to track privileged user activities
- Set up automated health checks for MySQL Server availability
- Monitor system resource utilization (CPU, memory) for MySQL Server processes
- Implement real-time alerting for database service interruptions
How to Mitigate CVE-2025-21534
Immediate Actions Required
- Apply the security patches provided in Oracle's January 2025 Critical Patch Update
- Review and restrict high-privilege account access to minimize attack surface
- Implement network segmentation to limit access to MySQL Server from untrusted networks
- Enable enhanced audit logging for privileged database operations
Patch Information
Oracle has released security patches addressing this vulnerability in the January 2025 Critical Patch Update (CPU). Affected organizations should upgrade their MySQL Server installations to the latest patched versions. Detailed patch information is available in the Oracle January 2025 CPU Security Alerts. Additional guidance is provided in the NetApp Security Advisory NTAP-20250124-0010.
Workarounds
- Restrict network access to MySQL Server to trusted hosts and networks only
- Implement strict access controls to limit the number of accounts with high privileges
- Monitor and audit all administrative actions on MySQL Server instances
- Consider disabling or limiting Performance Schema features if not required for operations
# Configuration example - Restrict MySQL bind address and implement firewall rules
# In my.cnf, limit MySQL to specific interface
bind-address = 127.0.0.1
# Use iptables/firewall to restrict MySQL port access
# iptables -A INPUT -p tcp --dport 3306 -s trusted_network/24 -j ACCEPT
# iptables -A INPUT -p tcp --dport 3306 -j DROP
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
