Invoice Ninja is a source-available invoice, quote, project and time-tracking app built with Laravel. Invoice line item descriptions in Invoice Ninja v5.13.0 bypass the XSS denylist filter, allowing stored XSS payloads to execute when invoices are rendered in the PDF preview or client portal. The line item description field was not passed through purify::clean() before rendering. This is fixed in v5.13.4 by the vendor by adding purify::clean() to sanitize line item descriptions.