Executive Summary

CVE-2026-30575 is a Business Logic vulnerability in the Pharmacy Product Management System version 1.0, specifically in the add-stock.php file responsible for stock entry.

The vulnerability occurs because the system fails to properly validate the input parameter 'txtqty', which is supposed to accept only positive integers to increase inventory stock.

An attacker can submit negative values for 'txtqty', causing the system to subtract from the current stock instead of adding to it. This allows unauthorized reduction or destruction of inventory records without needing delete permissions.

This can lead to inventory corruption and potentially cause a Denial of Service by depleting stock records, which may block legitimate sales if stock availability checks are enforced.

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Impact Analysis

This vulnerability can have several impacts on your system:

• Malicious reduction or destruction of inventory stock by submitting negative quantities.
• Corruption of stock-in data integrity, leading to inaccurate inventory records.
• Potential Denial of Service (DoS) by depleting stock levels to zero, which can block legitimate sales if the system checks stock availability before processing orders.

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Detection Guidance

This vulnerability can be detected by monitoring and inspecting POST requests to the add-stock.php endpoint, specifically looking for the parameter `txtqty` containing negative values.

An example approach is to capture HTTP traffic to the Add Stock page and check if any requests submit negative numbers in the `txtqty` parameter, which should normally only accept positive integers.

A proof-of-concept involves intercepting the 'Save' request and modifying the `txtqty` parameter to a negative value, such as -100.

• Use a network traffic capture tool like Wireshark or a proxy tool like Burp Suite to intercept POST requests to add-stock.php.
• Look for POST data containing `txtqty` with negative values.
• Example curl command to test the vulnerability by sending a negative quantity: curl -X POST -d "txtqty=-100" http://target/add-stock.php

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Mitigation Strategies

Immediate mitigation steps include implementing proper input validation on the `txtqty` parameter to ensure only positive integers are accepted.

Restrict or sanitize user input on the server side to reject negative values before processing stock updates.

Additionally, monitor inventory levels for unexpected decreases that could indicate exploitation.

If possible, temporarily disable the add-stock functionality or restrict access to trusted users until a patch or fix is applied.

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