Python: Use a Jinja2 sandboxed env to prevent running unsafe code. (m…

…icrosoft#6163)

### Motivation and Context

The `Jinja2PromptTemplate` allows users to integrate `Jinja2` as `Prompt
engine` within a `semantic-kernel` structure LLM application.
Nevertheless, `Jinja2PromptTemplate` directly takes **sandbox-less**
`jinja2.Environment` as `Jinja2 Environment`, allowing attackers to
escape and call arbitrary `__builtins__` methods such as `os.Popen`,
resulting possible RCE or further exploitations.

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### Description

This PR fixes this by implementing a SandboxedEnvironment to prevent
users from being able to run malicious code.
- All tests passing.

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### Contribution Checklist

<!-- Before submitting this PR, please make sure: -->

- [X] The code builds clean without any errors or warnings
- [X] The PR follows the [SK Contribution
Guidelines](https:/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md)
and the [pre-submission formatting
script](https:/microsoft/semantic-kernel/blob/main/CONTRIBUTING.md#development-scripts)
raises no violations
- [X] All unit tests pass, and I have added new tests where possible
- [X] I didn't break anyone 😄

python/semantic_kernel/prompt_template/jinja2_prompt_template.py

@@ -3,7 +3,8 @@
 import logging
 from typing import TYPE_CHECKING, Any, Optional
 
-from jinja2 import BaseLoader, Environment, TemplateError
+from jinja2 import BaseLoader, TemplateError
+from jinja2.sandbox import ImmutableSandboxedEnvironment
 from pydantic import PrivateAttr, field_validator
 
 from semantic_kernel.exceptions import Jinja2TemplateRenderException, Jinja2TemplateSyntaxError
@@ -43,7 +44,7 @@ class Jinja2PromptTemplate(PromptTemplateBase):
  Jinja2TemplateSyntaxError: If there is a syntax error in the Jinja2 template.
  """
 
- _env: Environment = PrivateAttr()
+ _env: ImmutableSandboxedEnvironment = PrivateAttr()
 
  @field_validator("prompt_template_config")
  @classmethod
@@ -57,7 +58,7 @@ def model_post_init(self, __context: Any) -> None:
  self._env = None
  return
  try:
- self._env = Environment(loader=BaseLoader())
+ self._env = ImmutableSandboxedEnvironment(loader=BaseLoader())
  except TemplateError as e:
  logger.error(f"Invalid jinja2 template: {self.prompt_template_config.template}")
  raise Jinja2TemplateSyntaxError(f"Invalid jinja2 template: {self.prompt_template_config.template}") from e