Akaunting 3.3.0 contains a stored cross-site scripting vulnerability in custom invoice payment terms. An authenticated Manager can save a crafted custom payment-term value. When an authorized user opens Invoice Settings for the same company, Akaunting inserts the stored value into a client-side event-handler expression, causing attacker-controlled JavaScript to execute in the victim's authenticated origin.
Use only predefined payment-term options, replace existing custom values, and restrict invoice-settings update access to trusted users until a vendor fix is available. Treat this as temporary mitigation rather than a fix.
Use a JavaScript-safe serializer such as Laravel Js::from() or a framework data binding for the custom payment-term value; validate it as a bounded integer when it represents a number of days; apply the vendor-fixed release once one is published.