CVE-2026-30575 Overview
A Business Logic vulnerability exists in SourceCodester Pharmacy Product Management System 1.0 in the add-stock.php file. The application fails to validate the txtqty parameter during stock entry, allowing negative values to be processed. This causes the system to decrease the inventory level instead of increasing it, leading to inventory corruption and potential Denial of Service by depleting stock records.
Critical Impact
Attackers can manipulate inventory levels by submitting negative quantity values, causing stock depletion and system disruption without requiring authentication.
Affected Products
- Senior-walter Web-based Pharmacy Product Management System 1.0
- SourceCodester Pharmacy Product Management System 1.0
Discovery Timeline
- 2026-03-27 - CVE CVE-2026-30575 published to NVD
- 2026-03-31 - Last updated in NVD database
Technical Details for CVE-2026-30575
Vulnerability Analysis
This vulnerability represents a classic Business Logic Error (CWE-20: Improper Input Validation) where the application fails to enforce expected business constraints on user-supplied data. The add-stock.php endpoint is designed to increase inventory quantities when new stock is received, but the lack of proper validation allows the business logic to be subverted.
When a user submits a stock addition request, the application processes the txtqty parameter without verifying that it contains a positive integer value. This oversight allows an attacker to submit negative values, which the system arithmetic processes as a subtraction operation rather than addition. The result is that inventory records are decremented instead of incremented, effectively allowing unauthorized stock manipulation.
The vulnerability can be exploited remotely over the network without any user interaction required, and notably does not require authentication to trigger. While the vulnerability does not directly expose confidential information or allow system compromise, it significantly impacts the availability and integrity of inventory data.
Root Cause
The root cause of this vulnerability is the absence of server-side input validation for the txtqty parameter in the add-stock.php file. The application trusts user-supplied input and directly uses the quantity value in database operations without first verifying that it meets the expected business constraints (i.e., positive integer values only). This represents a failure to implement proper input validation as a defensive programming practice.
Attack Vector
The attack is conducted over the network by sending HTTP requests to the add-stock.php endpoint with a negative value in the txtqty parameter. An attacker can craft malicious requests using standard tools such as browser developer tools, cURL, or automated scripts.
The exploitation process involves:
- Identifying the stock addition endpoint (add-stock.php)
- Capturing or constructing a valid stock addition request
- Modifying the txtqty parameter to contain a negative value
- Submitting the request to deplete inventory records
- Repeating the process to cause widespread inventory corruption or complete stock depletion
No authentication appears to be required to exploit this vulnerability, making it accessible to unauthenticated remote attackers. For detailed technical information and proof-of-concept examples, see the GitHub PoC Repository.
Detection Methods for CVE-2026-30575
Indicators of Compromise
- HTTP POST requests to add-stock.php containing negative values in the txtqty parameter
- Database records showing unexpected inventory decrements following stock addition operations
- Inventory audit logs revealing stock levels that decrease when additions were processed
- Multiple rapid requests to stock management endpoints from single IP addresses
Detection Strategies
- Implement web application firewall (WAF) rules to flag or block requests with negative numeric values in quantity parameters
- Deploy application-layer monitoring to detect anomalous patterns in stock management operations
- Enable detailed logging of all stock modification operations including source IP, user session, and parameter values
- Configure database triggers or audit tables to track all inventory level changes with associated request metadata
Monitoring Recommendations
- Monitor web server access logs for suspicious patterns of requests to add-stock.php
- Set up alerts for inventory records that drop below expected thresholds or reach zero unexpectedly
- Implement real-time monitoring of stock management transactions to detect rapid or automated manipulation attempts
- Review application logs regularly for evidence of business logic abuse patterns
How to Mitigate CVE-2026-30575
Immediate Actions Required
- Implement server-side validation to reject negative values in the txtqty parameter immediately
- Consider restricting access to the add-stock.php endpoint to authenticated and authorized users only
- Deploy temporary WAF rules to block requests containing negative quantity values
- Audit existing inventory records to identify and correct any data corruption from exploitation
Patch Information
No official patch has been released by the vendor at the time of this publication. Organizations using this software should implement the workarounds described below and monitor for vendor updates. The vulnerability affects Senior-walter Web-based Pharmacy Product Management System version 1.0.
For more information and proof-of-concept details, refer to the GitHub PoC Repository.
Workarounds
- Add server-side validation in add-stock.php to ensure txtqty parameter only accepts positive integer values
- Implement authentication and authorization controls to restrict access to stock management functions
- Deploy a web application firewall with rules to detect and block negative quantity submissions
- Consider using stored procedures with built-in validation at the database layer as an additional defense
# Example Apache mod_rewrite rule to block negative quantities (temporary mitigation)
# Add to .htaccess or Apache configuration
RewriteEngine On
RewriteCond %{REQUEST_METHOD} POST
RewriteCond %{REQUEST_URI} /add-stock\.php
RewriteCond %{QUERY_STRING} txtqty=-[0-9]+ [OR]
RewriteCond %{THE_REQUEST} txtqty=-[0-9]+
RewriteRule .* - [F,L]
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
