CVE-2020-5504: phpMyAdmin SQL Injection Vulnerability

CVE-2020-5504 Overview

CVE-2020-5504 is a SQL injection vulnerability affecting phpMyAdmin versions 4.x before 4.9.4 and 5.x before 5.0.1. The vulnerability exists in the user accounts page where a malicious user could inject custom SQL statements in place of their own username when creating queries to this page. While exploitation requires the attacker to have a valid MySQL account to access the server, successful exploitation could lead to unauthorized database access, data manipulation, or complete database compromise.

Critical Impact

Authenticated attackers can execute arbitrary SQL commands against the database, potentially leading to data exfiltration, modification, or destruction of database contents.

Affected Products

• phpMyAdmin versions 4.x before 4.9.4
• phpMyAdmin versions 5.x before 5.0.1
• SUSE Linux Enterprise Server 12 (bundled phpMyAdmin)
• Debian Linux 8.0 (bundled phpMyAdmin)

Discovery Timeline

• 2020-01-09 - CVE-2020-5504 published to NVD
• 2025-04-16 - Last updated in NVD database

Technical Details for CVE-2020-5504

Vulnerability Analysis

This SQL injection vulnerability resides in phpMyAdmin's user accounts management functionality. The root cause is insufficient input sanitization when handling username parameters within queries to the user accounts page. When an authenticated user accesses this page, the application fails to properly escape or parameterize user-supplied input, allowing an attacker to break out of the intended SQL query context and inject malicious SQL statements.

The vulnerability is classified under CWE-89 (SQL Injection), indicating improper neutralization of special elements used in SQL commands. The attack can be executed remotely over the network with low complexity, though it requires the attacker to have low-level privileges (a valid MySQL account). No user interaction is required for exploitation, and successful attacks can result in high impact to confidentiality, integrity, and availability of the database.

Root Cause

The vulnerability stems from improper input validation in the user accounts page functionality. When phpMyAdmin constructs SQL queries involving usernames, it fails to adequately sanitize or parameterize user input. This allows specially crafted input containing SQL metacharacters to be interpreted as part of the SQL query rather than as data, enabling attackers to manipulate query logic.

Attack Vector

The attack vector is network-based, requiring an authenticated attacker with valid MySQL credentials. The attacker crafts a malicious username value containing SQL injection payloads when interacting with the user accounts page. Since the application uses the username directly in SQL queries without proper sanitization, the injected SQL code is executed against the database server.

The vulnerability allows attackers to inject custom SQL in place of their username parameter. This can be leveraged to extract sensitive data from other database tables, modify or delete data, escalate privileges within the database, or potentially gain further access to the underlying system depending on database configuration.

For technical details on the vulnerability mechanism and proof-of-concept information, refer to the phpMyAdmin Security Advisory and the GitHub PoC documentation.

Detection Methods for CVE-2020-5504

Indicators of Compromise

• Unusual SQL error messages in phpMyAdmin logs indicating malformed queries or syntax errors
• Database audit logs showing unexpected queries containing SQL keywords in username fields (e.g., UNION, SELECT, OR 1=1)
• Abnormal database access patterns from authenticated users accessing the user accounts page
• Evidence of data exfiltration or unauthorized data modifications in database transaction logs

Detection Strategies

• Implement web application firewall (WAF) rules to detect SQL injection patterns in HTTP requests to phpMyAdmin
• Monitor database query logs for anomalous queries originating from the phpMyAdmin application
• Deploy intrusion detection system (IDS) signatures that identify common SQL injection attack payloads
• Enable detailed logging on phpMyAdmin and correlate with database audit logs to identify suspicious activity

Monitoring Recommendations

• Configure alerting for SQL syntax errors or injection-related database exceptions in phpMyAdmin error logs
• Implement real-time monitoring of the user accounts page for requests containing SQL metacharacters
• Set up database activity monitoring to track privileged operations executed through phpMyAdmin
• Review authentication logs for unusual login patterns followed by user accounts page access

How to Mitigate CVE-2020-5504

Immediate Actions Required

• Upgrade phpMyAdmin to version 4.9.4 or later for the 4.x branch immediately
• Upgrade phpMyAdmin to version 5.0.1 or later for the 5.x branch immediately
• Apply vendor security patches from SUSE and Debian if using bundled phpMyAdmin packages
• Restrict network access to phpMyAdmin to trusted IP addresses or VPN connections only
• Review database user privileges to apply principle of least privilege

Patch Information

phpMyAdmin has released patched versions that address this SQL injection vulnerability. Version 4.9.4 resolves the issue for the 4.x branch, while version 5.0.1 addresses it for the 5.x branch. Organizations should apply these updates immediately by downloading the latest release from the official phpMyAdmin website or through their distribution's package manager.

For detailed patch information and security guidance, refer to the phpMyAdmin Security Advisory PMASA-2020-1. Linux distribution users should also consult the Debian LTS Security Notice and openSUSE Security Announcement for distribution-specific patches.

Workarounds

• Restrict access to the phpMyAdmin user accounts page to only trusted administrator accounts
• Implement network-level access controls (firewall rules, VPN requirements) to limit who can access phpMyAdmin
• Place phpMyAdmin behind a reverse proxy with WAF capabilities to filter SQL injection attempts
• Temporarily disable phpMyAdmin access until patches can be applied in critical environments

# Apache configuration to restrict phpMyAdmin access
<Directory /usr/share/phpmyadmin>
    Order Deny,Allow
    Deny from all
    Allow from 192.168.1.0/24
    Allow from 10.0.0.0/8
</Directory>