CVE-2021-47811: Grocery Crud SQLi Vulnerability

CVE-2021-47811 Overview

CVE-2021-47811 is a SQL injection vulnerability affecting Grocery Crud version 1.6.4, a popular PHP CRUD (Create, Read, Update, Delete) generator library. The vulnerability exists in the order_by parameter, allowing remote attackers to manipulate database queries by injecting malicious SQL code through the order_by[] parameter in POST requests to the ajax_list endpoint. Successful exploitation could allow attackers to extract, modify, or delete sensitive database information.

Critical Impact

Remote attackers can exploit this SQL injection vulnerability to access or manipulate sensitive database contents without authentication, potentially leading to data breaches or unauthorized data modification.

Affected Products

• Grocery Crud version 1.6.4
• Web applications utilizing vulnerable Grocery Crud library versions
• PHP-based applications with exposed ajax_list endpoints

Discovery Timeline

• 2026-01-16 - CVE CVE-2021-47811 published to NVD
• 2026-01-16 - Last updated in NVD database

Technical Details for CVE-2021-47811

Vulnerability Analysis

This SQL injection vulnerability (CWE-89) occurs due to improper input validation in Grocery Crud's order_by parameter handling. The library fails to properly sanitize user-supplied input before incorporating it into SQL queries, creating an injection point that attackers can exploit.

When processing AJAX requests for listing data, the application accepts an order_by[] array parameter that controls the sorting of database results. The parameter value is directly interpolated into the ORDER BY clause of SQL queries without adequate input sanitization or parameterized query usage. This allows attackers to break out of the intended query context and inject arbitrary SQL commands.

The network-accessible nature of this vulnerability means attackers can exploit it remotely without requiring any form of authentication or user interaction. This significantly increases the attack surface as any internet-facing application using the vulnerable Grocery Crud version becomes a potential target.

Root Cause

The root cause is insufficient input validation and lack of prepared statements when handling the order_by[] parameter in the ajax_list endpoint. The application directly concatenates user input into SQL queries without proper escaping or parameterization, violating secure coding practices for database interactions.

Attack Vector

The attack is conducted over the network by sending specially crafted POST requests to the application's ajax_list endpoint. Attackers manipulate the order_by[] parameter to inject malicious SQL code that gets executed by the database server. The injection payload can be crafted to extract database schema information, dump table contents, modify records, or potentially escalate to more severe attacks depending on database permissions and configuration.

A typical attack involves crafting a POST request where the order_by[] parameter contains SQL syntax designed to break out of the ORDER BY clause. Attackers can use techniques such as UNION-based injection, time-based blind injection, or error-based injection depending on the application's response behavior. For detailed technical analysis and proof-of-concept information, refer to the Exploit-DB #49985 entry or the VulnCheck Advisory on SQL Injection.

Detection Methods for CVE-2021-47811

Indicators of Compromise

• Unusual or malformed order_by[] parameter values in POST requests to ajax_list endpoints
• Database error messages in application logs indicating SQL syntax errors
• Unexpected database queries or abnormal query patterns in database logs
• Evidence of data exfiltration or unauthorized database access

Detection Strategies

• Monitor web application logs for POST requests containing SQL injection patterns in the order_by[] parameter
• Deploy Web Application Firewall (WAF) rules to detect and block SQL injection payloads targeting ORDER BY clauses
• Implement database activity monitoring to identify anomalous queries or unauthorized data access
• Use intrusion detection systems with signatures for common SQL injection attack patterns

Monitoring Recommendations

• Enable detailed logging for all requests to ajax_list endpoints and review regularly
• Configure database audit logging to track queries containing ORDER BY modifications
• Set up alerts for error patterns indicative of SQL injection attempts
• Monitor outbound network traffic for signs of data exfiltration

How to Mitigate CVE-2021-47811

Immediate Actions Required

• Upgrade Grocery Crud to the latest available version from the official downloads page
• Implement input validation and sanitization for all user-supplied parameters
• Deploy a Web Application Firewall (WAF) with SQL injection protection enabled
• Review application logs for evidence of prior exploitation attempts

Patch Information

Users should upgrade to a patched version of Grocery Crud. Visit the Grocery CRUD Official Site for the latest security updates and release information. Review the VulnCheck Advisory on SQL Injection for additional guidance on remediation steps.

Workarounds

• Implement server-side input validation to whitelist allowed order_by column names
• Use parameterized queries or prepared statements for all database interactions
• Restrict access to ajax_list endpoints using authentication and authorization controls
• Deploy application-level filtering to reject requests containing SQL injection patterns

# Example Apache ModSecurity rule to block SQL injection in order_by parameter
SecRule ARGS:order_by[] "@detectSQLi" \
    "id:1001,\
    phase:2,\
    block,\
    msg:'SQL Injection attempt detected in order_by parameter',\
    logdata:'Matched Data: %{MATCHED_VAR}',\
    severity:'CRITICAL'"