InvenTree is an Open Source Inventory Management System. Prior to version 1.2.3, insecure server-side templates can be hijacked to expose secure information to the client. When generating custom batch codes, the InvenTree server makes use of a customizable jinja2 template, which can be modified by a staff user to exfiltrate sensitive information or perform code execution on the server. This issue requires access by a user with granted staff permissions, followed by a request to generate a custom batch code via the API. Once the template has been modified in a malicious manner, the API call to generate a new batch code could be made by other users, and the template code will be executed with their user context. The code has been patched to ensure that all template generation is performed within a secure sandboxed context. This issue has been addressed in version 1.2.3, and any versions from 1.3.0 onwards. Some workarounds are available. The batch code template is a configurable global setting which can be adjusted via any user with staff access. To prevent this setting from being edited, it can be overridden at a system level to a default value, preventing it from being edited. This requires system administrator access, and cannot be changed from the client side once the server is running. It is recommended that for InvenTree installations prior to 1.2.3 the STOCK_BATCH_CODE_TEMPLATE and PART_NAME_FORMAT global settings are overridden at the system level to prevent editing.
Weakness
The product uses a template engine to insert or process externally-influenced input, but it does not neutralize or incorrectly neutralizes special elements or syntax that can be interpreted as template expressions or other code directives when processed by the engine.
Affected Software
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Inventree | Inventree_project | * | 1.2.3 (excluding) |
Extended Description
Many web applications use template engines that allow developers to insert externally-influenced values into free text or messages in order to generate a full web page, document, message, etc. Such engines include Twig, Jinja2, Pug, Java Server Pages, FreeMarker, Velocity, ColdFusion, Smarty, and many others - including PHP itself. Some CMS (Content Management Systems) also use templates. Template engines often have their own custom command or expression language. If an attacker can influence input into a template before it is processed, then the attacker can invoke arbitrary expressions, i.e. perform injection attacks. For example, in some template languages, an attacker could inject the expression “{{7*7}}” and determine if the output returns “49” instead. The syntax varies depending on the language. In some cases, XSS-style attacks can work, which can obscure the root cause if the developer does not closely investigate the root cause of the error. Template engines can be used on the server or client, so both “sides” could be affected by injection. The mechanisms of attack or the affected technologies might be different, but the mistake is fundamentally the same.