InvoicePlane is a self-hosted open source application for managing invoices, clients, and payments. A Stored Cross-Site Scripting (XSS) vulnerability occurs in the Edit Quotes functions of InvoicePlane version 1.7.0. In the Editing Quotes function, the application does not validate user input at the quote_number parameter. Although administrator privileges are required to exploit it, this is still considered a critical vulnerability as it can cause actions such as unauthorized modification of application data, creation of persistent backdoors through stored malicious scripts, and full compromise of the application's integrity. Version 1.7.1 patches the issue.