CVE-2021-2144: Oracle MySQL Server Parser RCE Vulnerability

CVE-2021-2144 Overview

CVE-2021-2144 is a vulnerability in the MySQL Server product of Oracle MySQL, specifically affecting the Server Parser component. This easily exploitable vulnerability allows a high-privileged attacker with network access via multiple protocols to completely compromise the MySQL Server. Successful exploitation results in a complete takeover of the MySQL Server, impacting confidentiality, integrity, and availability of the database system.

Critical Impact

Successful exploitation enables complete takeover of MySQL Server, allowing attackers with high privileges to gain full control over database operations, data access, and system integrity.

Affected Products

• Oracle MySQL versions 5.7.29 and prior
• Oracle MySQL versions 8.0.19 and prior
• NetApp Active IQ Unified Manager (VMware vSphere and Windows)
• NetApp OnCommand Insight
• NetApp OnCommand Workflow Automation
• NetApp SnapCenter
• MariaDB (multiple versions)

Discovery Timeline

• April 22, 2021 - CVE-2021-2144 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2021-2144

Vulnerability Analysis

This vulnerability resides in the MySQL Server Parser component, which is responsible for processing and interpreting SQL queries and commands. The parser is a critical component that handles all incoming SQL statements before they are executed by the database engine. A flaw in this component can allow malicious input to bypass security controls or cause unintended behavior.

The vulnerability requires high-privileged access, meaning an attacker must already possess administrative or elevated credentials to the MySQL Server. However, once authenticated, the attacker can exploit the parser flaw through network-accessible protocols to achieve complete server compromise. This includes unauthorized access to all data, modification of database contents, and disruption of database availability.

Root Cause

The vulnerability stems from insufficient input validation or improper handling within the MySQL Server Parser component. While Oracle has not disclosed specific technical details about the root cause (classified as NVD-CWE-noinfo), parser vulnerabilities typically arise from:

• Improper parsing of specially crafted SQL statements
• Boundary condition errors in query processing
• Memory handling issues during complex query parsing operations
• Type confusion or state management flaws in the parser state machine

The parser must handle complex SQL syntax, nested queries, and various character encodings, making it a historically challenging component to secure.

Attack Vector

The attack vector is network-based and can be exploited via multiple protocols supported by MySQL Server. An attacker with high-privileged credentials can connect remotely to the MySQL Server and submit specially crafted SQL statements or commands that exploit the parser vulnerability.

The exploitation scenario involves:

1. An attacker obtaining or possessing high-privileged MySQL credentials
2. Establishing a network connection to the target MySQL Server
3. Submitting malicious input that triggers the parser vulnerability
4. Achieving complete server takeover with full control over database operations

The vulnerability is described as "easily exploitable," indicating that once the prerequisite credentials are obtained, the actual exploitation requires minimal technical complexity.

Detection Methods for CVE-2021-2144

Indicators of Compromise

• Unusual SQL query patterns or syntax errors in MySQL error logs
• Unexpected database connections from unauthorized network locations using privileged accounts
• Anomalous parser-related errors or crashes in MySQL server logs
• Unauthorized data access, modification, or extraction activities

Detection Strategies

• Monitor MySQL general query logs and slow query logs for unusual or malformed SQL statements
• Implement database activity monitoring (DAM) to detect suspicious privileged user behavior
• Deploy intrusion detection systems (IDS) with MySQL-specific signatures to identify exploitation attempts
• Review MySQL error logs for parser-related exceptions or unexpected terminations

Monitoring Recommendations

• Enable MySQL audit logging to track all privileged user activities and query executions
• Configure alerts for connections using high-privileged accounts from unexpected IP addresses or networks
• Establish baseline behavior patterns for database administrators and alert on deviations
• Monitor for database replication inconsistencies that may indicate data tampering

How to Mitigate CVE-2021-2144

Immediate Actions Required

• Upgrade Oracle MySQL Server to version 5.7.30 or later for the 5.7.x branch
• Upgrade Oracle MySQL Server to version 8.0.20 or later for the 8.0.x branch
• Apply the Oracle Critical Patch Update April 2021
• Review and audit all high-privileged MySQL accounts and credentials

Patch Information

Oracle addressed this vulnerability in the April 2021 Critical Patch Update. Organizations should apply the latest security patches from Oracle or upgrade to the fixed versions. For NetApp products, refer to the NetApp Security Advisory NTAP-20210513-0002 for product-specific guidance.

Affected versions requiring updates:

• MySQL 5.7.29 and prior → Upgrade to 5.7.30 or later
• MySQL 8.0.19 and prior → Upgrade to 8.0.20 or later

Workarounds

• Restrict network access to MySQL Server using firewall rules to limit exposure
• Implement strong authentication controls and multi-factor authentication for privileged accounts
• Apply the principle of least privilege to reduce the number of high-privileged database users
• Isolate database servers in separate network segments with strict access controls

# Restrict MySQL access to trusted networks only
# Edit MySQL configuration file (my.cnf or my.ini)
[mysqld]
bind-address = 127.0.0.1
# Or specify trusted internal network interface

# Use firewall rules 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