CVE-2023-21982 Overview
CVE-2023-21982 is a vulnerability in the MySQL Server product of Oracle MySQL, specifically affecting the Server: Optimizer component. This vulnerability allows a high privileged attacker with network access via multiple protocols to compromise MySQL Server, resulting in a complete denial of service condition through a hang or frequently repeatable crash.
Critical Impact
Successful exploitation enables attackers to cause complete denial of service (DoS) of MySQL Server, disrupting database availability for all dependent applications and services.
Affected Products
- Oracle MySQL Server 8.0.32 and prior versions
- MySQL deployments accessible via network protocols
- Systems utilizing the MySQL Server Optimizer component
Discovery Timeline
- April 18, 2023 - CVE-2023-21982 published to NVD
- April 2023 - Oracle releases security patch in Critical Patch Update
- November 21, 2024 - Last updated in NVD database
Technical Details for CVE-2023-21982
Vulnerability Analysis
This vulnerability resides within the Optimizer component of MySQL Server, which is responsible for determining the most efficient execution plan for SQL queries. The flaw is classified as easily exploitable, meaning that once an attacker has the required high-level privileges and network access, exploitation requires minimal complexity.
The vulnerability's impact is limited to availability—there is no compromise of data confidentiality or integrity. However, the ability to cause a complete denial of service means that database-dependent applications can be rendered inoperable during an attack.
Root Cause
The root cause stems from improper handling within the MySQL Server Optimizer component. While Oracle has not disclosed specific technical details about the underlying flaw (classified as NVD-CWE-noinfo), the vulnerability allows specially crafted operations to trigger a crash or hang condition in the server process.
The Optimizer component processes complex query plans and resource allocation decisions. Malformed or maliciously crafted queries exploiting this vulnerability can cause the optimizer to enter an unstable state, leading to service disruption.
Attack Vector
The attack requires network access to the MySQL Server and high-level privileges (such as administrative or DBA-level access). An authenticated attacker can leverage multiple protocols supported by MySQL to reach the vulnerable Optimizer component.
The attack scenario involves:
- Attacker gains high-privileged access to the MySQL Server (e.g., compromised admin credentials or insider threat)
- Attacker connects to the MySQL Server via network protocols
- Attacker executes operations that trigger the vulnerable code path in the Optimizer
- MySQL Server experiences a hang or crash, resulting in complete denial of service
- Service remains unavailable until manually restarted or recovered
No public proof-of-concept exploits have been identified for this vulnerability, and it is not currently listed in CISA's Known Exploited Vulnerabilities catalog.
Detection Methods for CVE-2023-21982
Indicators of Compromise
- Unexpected MySQL Server crashes or hangs without clear system resource exhaustion
- Abnormal query patterns from high-privileged accounts, particularly complex optimizer-intensive queries
- Repeated service restarts or recovery events in MySQL error logs
- Unusual network connections to MySQL ports from unexpected sources
Detection Strategies
- Monitor MySQL error logs for crash signatures related to the Optimizer component
- Implement query logging and analysis for anomalous patterns from privileged accounts
- Deploy database activity monitoring (DAM) solutions to track privileged user actions
- Configure alerting for MySQL service availability and unexpected restarts
Monitoring Recommendations
- Enable MySQL general query log or slow query log for forensic analysis during incidents
- Implement real-time monitoring of MySQL Server process health and availability
- Track authentication events for high-privileged accounts and correlate with query activity
- Set up automated alerting for MySQL service state changes and crash events
How to Mitigate CVE-2023-21982
Immediate Actions Required
- Upgrade MySQL Server to a patched version released after April 2023
- Audit and restrict high-privileged account access to only essential personnel
- Implement network segmentation to limit MySQL Server exposure
- Review and enforce the principle of least privilege for database accounts
Patch Information
Oracle has addressed this vulnerability in the April 2023 Critical Patch Update. Organizations should upgrade to MySQL Server versions released after 8.0.32 to remediate this vulnerability. Detailed patch information is available in the Oracle Critical Patch Update Advisory.
Additional vendor guidance is available from the NetApp Security Advisory for environments utilizing NetApp products with MySQL dependencies.
Workarounds
- Restrict network access to MySQL Server using firewall rules to allow only trusted IP addresses
- Implement strong authentication mechanisms and credential management for privileged accounts
- Enable MySQL audit logging to detect and investigate suspicious privileged account activity
- Consider deploying a database firewall to filter potentially malicious queries before they reach the server
# 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
# Verify MySQL version to confirm patch status
mysql --version
# Ensure version is greater than 8.0.32
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
