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.
Scope | Impact | Likelihood |
---|---|---|
Integrity | Execute Unauthorized Code or Commands |
Reference | Description |
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Chain: Python bindings for LLM library do not use a sandboxed environment when parsing a template and constructing a prompt, allowing jinja2 Server Side Template Injection and code execution - one variant of a "prompt injection" attack. | |
server-side template injection in content management server | |
authentication / identity management product has client-side template injection | |
Server-Side Template Injection using a Twig template | |
devops platform allows SSTI | |
bypass of Server-Side Template Injection protection mechanism with macros in Velocity templates | |
web browser proxy server allows Java EL expressions from Server-Side Template Injection | |
SSTI involving mail templates and JEXL expressions | |
product does not use a "safe" setting for a FreeMarker configuration, allowing SSTI | |
product allows read of sensitive database username/password variables using server-side template injection |
Name | Organization | Date | Date Release | Version |
---|---|---|---|---|
CWE Content Team | MITRE | 4.5 |
Name | Organization | Date | Comment |
---|---|---|---|
CWE Content Team | MITRE | updated Maintenance_Notes, Relationships | |
CWE Content Team | MITRE | updated Relationships | |
CWE Content Team | MITRE | updated Mapping_Notes | |
CWE Content Team | MITRE | updated Applicable_Platforms, Observed_Examples |