Executive brief
The SourceCodester Loan Management System is a web application used to manage financial loan products and interest rates. A flaw in the system allows users with administrative access to create loan plans with negative interest rates by bypassing the visual safety checks in the web browser. This could lead to significant financial data corruption, incorrect loan calculations, and operational disruption within the lending platform.
Technical details
A business logic vulnerability exists in the Plan Management component (specifically ajax.php?action=save_plan) of SourceCodester Loan Management System v1.0. While the frontend UI uses HTML5 or JavaScript constraints to prevent negative values in the 'interest_percentage' field, the backend fails to validate that the submitted value is non-negative. An authenticated attacker can intercept and modify the HTTP POST request (e.g., using Burp Suite or curl) to inject a negative interest rate. This results in the storage of invalid financial parameters in the database, which can break downstream interest calculations and financial reporting. No patch is currently documented in the advisory.
Affected products
- SourceCodester Loan Management System 1.0
Timeline
- 2026-03-31: disclosed: Initial disclosure of CVE-2026-30521
- 2026-03-31: advisory: NVD publication date