CVE-2020-26935: phpMyAdmin Search SQLi Vulnerability

CVE-2020-26935 Overview

CVE-2020-26935 is a SQL injection vulnerability discovered in the SearchController component of phpMyAdmin, a widely-used open-source web-based database administration tool. The flaw exists in how phpMyAdmin processes SQL statements within its search feature, allowing attackers to inject malicious SQL queries. This vulnerability affects phpMyAdmin versions before 4.9.6 and 5.x before 5.0.3.

Critical Impact

This SQL injection vulnerability allows unauthenticated attackers to inject malicious SQL statements through the search feature, potentially leading to unauthorized data access, data manipulation, or complete database compromise.

Affected Products

• phpMyAdmin versions prior to 4.9.6
• phpMyAdmin 5.x versions prior to 5.0.3
• openSUSE Backports SLE 15.0, 15.0 SP1, 15.0 SP2
• openSUSE Leap 15.1 and 15.2
• Fedora 31, 32, and 33
• Debian Linux 9.0

Discovery Timeline

• October 10, 2020 - CVE-2020-26935 published to NVD
• November 21, 2024 - Last updated in NVD database

Technical Details for CVE-2020-26935

Vulnerability Analysis

This SQL injection vulnerability (CWE-89) resides in the SearchController component of phpMyAdmin. The vulnerability stems from improper sanitization of user-supplied input when processing SQL statements through the application's search functionality. An attacker can exploit this flaw by crafting specially malformed input that bypasses input validation, allowing arbitrary SQL code to be executed against the underlying database.

The attack can be performed remotely over the network without requiring any authentication or user interaction. Successful exploitation could allow an attacker to read sensitive information from the database, modify or delete data, execute administrative operations on the database, and in some configurations, potentially execute commands on the underlying operating system.

Root Cause

The root cause of this vulnerability is improper input validation and insufficient sanitization of user-controlled data within the SearchController component. When processing search queries, the application fails to properly escape or parameterize user input before incorporating it into SQL statements. This allows specially crafted input containing SQL syntax to be interpreted as part of the query rather than as literal data, enabling SQL injection attacks.

Attack Vector

The attack vector is network-based, targeting the phpMyAdmin web interface. An attacker can exploit this vulnerability by:

1. Accessing the phpMyAdmin search feature through the web interface
2. Submitting a specially crafted search query containing malicious SQL payloads
3. The SearchController component processes the input without proper sanitization
4. The malicious SQL is executed against the database with the privileges of the phpMyAdmin database user

The vulnerability is particularly dangerous because phpMyAdmin typically has elevated database privileges to perform administrative tasks. For detailed technical information, refer to the phpMyAdmin Security Advisory PMASA-2020-6 and the Checkmarx Security Advisory CX-2020-4281.

Detection Methods for CVE-2020-26935

Indicators of Compromise

• Unusual or malformed HTTP requests targeting phpMyAdmin search endpoints
• Database query logs showing unexpected SQL syntax, UNION-based injections, or time-based blind injection patterns
• Error messages in application logs indicating SQL syntax errors from malformed queries
• Unexpected database operations or data exfiltration attempts

Detection Strategies

• Monitor web server access logs for suspicious requests to phpMyAdmin search functionality containing SQL injection patterns
• Implement Web Application Firewall (WAF) rules to detect and block common SQL injection payloads
• Enable database query logging and analyze for anomalous query patterns or unauthorized data access
• Deploy network intrusion detection systems (IDS) with signatures for SQL injection attacks

Monitoring Recommendations

• Configure alerts for repeated failed database queries that may indicate injection attempts
• Monitor for unusual database user activity, particularly read operations on sensitive tables
• Implement real-time log analysis for phpMyAdmin access patterns
• Track and alert on any changes to database schema or administrative operations

How to Mitigate CVE-2020-26935

Immediate Actions Required

• Upgrade phpMyAdmin to version 4.9.6 or later (for 4.x series) or 5.0.3 or later (for 5.x series) immediately
• If immediate patching is not possible, restrict access to phpMyAdmin to trusted IP addresses only
• Review database logs for any signs of exploitation or unauthorized access
• Ensure phpMyAdmin is not exposed to the public internet without proper access controls

Patch Information

phpMyAdmin has released security patches addressing this vulnerability. Organizations should update to the following versions:

• phpMyAdmin 4.x series: Upgrade to version 4.9.6 or later
• phpMyAdmin 5.x series: Upgrade to version 5.0.3 or later

Patches are available through the official phpMyAdmin website and distribution-specific package repositories. For detailed information, see the phpMyAdmin Security Advisory PMASA-2020-6.

Linux distributions have also released security updates:

• Debian LTS Security Announcement
• Gentoo GLSA 202101-35
• openSUSE and Fedora have released package updates through their respective security channels

Workarounds

• Restrict network access to phpMyAdmin using firewall rules or .htaccess configuration to allow only trusted IP addresses
• Implement a Web Application Firewall (WAF) with SQL injection detection rules in front of phpMyAdmin
• Disable the search functionality if not required until patching is complete
• Use VPN or SSH tunneling to access phpMyAdmin instead of exposing it directly to the network

# Apache .htaccess example 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>