CVE-2026-3793: Sales And Inventory System SQLi Vulnerability

CVE-2026-3793 Overview

A SQL Injection vulnerability has been identified in SourceCodester Sales and Inventory System version 1.0. This vulnerability affects the sales_invoice1.php file within the GET Parameter Handler component. By manipulating the sellid argument, an attacker can inject malicious SQL statements that are executed by the backend database. The vulnerability is remotely exploitable and proof-of-concept exploit code has been publicly disclosed.

Critical Impact

Remote attackers with low-level privileges can exploit this SQL injection vulnerability to extract, modify, or delete database contents, potentially leading to unauthorized access to sensitive sales and inventory data.

Affected Products

• SourceCodester Sales and Inventory System 1.0

Discovery Timeline

• March 9, 2026 - CVE-2026-3793 published to NVD
• March 9, 2026 - Last updated in NVD database

Technical Details for CVE-2026-3793

Vulnerability Analysis

This SQL Injection vulnerability (CWE-89) occurs within the sales_invoice1.php file when processing the sellid GET parameter. The application fails to properly sanitize or parameterize user-supplied input before incorporating it into SQL queries executed against the backend database. This classic injection flaw allows authenticated attackers with minimal privileges to manipulate database queries directly.

The vulnerability is classified under CWE-74 (Improper Neutralization of Special Elements in Output Used by a Downstream Component) and CWE-89 (Improper Neutralization of Special Elements used in an SQL Command). Attackers can leverage this flaw remotely over the network without requiring any user interaction.

Root Cause

The root cause of this vulnerability is the direct concatenation or improper handling of user-supplied input from the sellid GET parameter into SQL queries without proper input validation, sanitization, or the use of parameterized queries (prepared statements). The PHP code in sales_invoice1.php does not implement adequate security controls to prevent malicious SQL syntax from being interpreted by the database engine.

Attack Vector

The attack can be initiated remotely by an authenticated attacker over the network. The attacker crafts a malicious HTTP GET request to sales_invoice1.php with a specially crafted sellid parameter containing SQL injection payloads. Upon receiving the request, the vulnerable application processes the malicious input and executes the injected SQL commands against the database. Successful exploitation could allow an attacker to:

• Extract sensitive data from the database including sales records, customer information, and inventory data
• Modify or delete database records
• Potentially escalate privileges within the application
• In some configurations, execute operating system commands via database functionality

Technical details and proof-of-concept information are available in the GitHub SQLi Proof of Concept documentation.

Detection Methods for CVE-2026-3793

Indicators of Compromise

• HTTP requests to sales_invoice1.php containing SQL syntax characters in the sellid parameter (e.g., single quotes, UNION, SELECT, OR 1=1)
• Database error messages appearing in HTTP responses indicating SQL syntax errors
• Unusual database queries in backend logs showing multiple queries or unexpected UNION statements
• Abnormal data access patterns or bulk data extraction from sales and inventory tables

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block SQL injection patterns in HTTP GET parameters
• Monitor application logs for requests to sales_invoice1.php with suspicious sellid parameter values
• Enable database query logging to identify anomalous SQL statements originating from the web application
• Deploy intrusion detection systems (IDS) with SQL injection signature sets

Monitoring Recommendations

• Establish baseline metrics for normal database query patterns and alert on deviations
• Configure real-time alerting for multiple failed database queries from the same source IP
• Monitor for data exfiltration indicators such as large result sets or time-based delays in responses
• Implement file integrity monitoring on web application files to detect unauthorized modifications

How to Mitigate CVE-2026-3793

Immediate Actions Required

• Restrict access to sales_invoice1.php using network-level controls or authentication requirements
• Implement input validation to allow only numeric values in the sellid parameter
• Deploy a Web Application Firewall (WAF) with SQL injection protection rules
• Review database user permissions and implement least-privilege access for the application's database account
• Consider temporarily disabling the affected functionality until a permanent fix is applied

Patch Information

At the time of publication, no official vendor patch has been released for this vulnerability. Organizations using SourceCodester Sales and Inventory System 1.0 should monitor the SourceCodester website for security updates. Additional vulnerability intelligence is available through VulDB #349760.

Workarounds

• Modify the sales_invoice1.php file to use parameterized queries (prepared statements) with PDO or MySQLi
• Implement server-side input validation to enforce that sellid contains only expected numeric values
• Add a Web Application Firewall rule specifically blocking SQL injection attempts in the sellid parameter
• Restrict network access to the application to trusted IP addresses only

# Example Apache .htaccess rule to restrict access to vulnerable file
<Files "sales_invoice1.php">
    Order Deny,Allow
    Deny from all
    Allow from 192.168.1.0/24
</Files>