Giskard is an open-source Python library for testing and evaluating agentic systems. Prior to versions 0.3.4 and 1.0.2b1, ChatWorkflow.chat(message) passes its string argument directly as a Jinja2 template source to a non-sandboxed Environment. A developer who passes user input to this method enables full remote code execution via Jinja2 class traversal. The method name chat and parameter name message naturally invite passing user input directly, but the string is silently parsed as a Jinja2 template, not treated as plain text. This issue has been patched in versions 0.3.4 and 1.0.2b1.

Affected: PyPI: giskard-agents

## Summary

`ChatWorkflow.chat(message)` passes its string argument directly as a Jinja2 template source to a non-sandboxed `Environment`. A developer who passes user input to this method enables full remote code execution via Jinja2 class traversal.

The method name `chat` and parameter name `message` naturally invite passing user input directly, but the string is silently parsed as a Jinja2 template, not treated as plain text.

## Root Cause

`libs/giskard-agents/src/giskard/agents/workflow.py` line ~261: ```python def chat(self, message: str | Message | MessageTemplate, role: Role = "user") -> Self: if isinstance(message, str): message = MessageTemplate(role=role, content_template=message) ```

The string becomes `content_template`, which is parsed by `from_string()`:

`libs/giskard-agents/src/giskard/agents/templates/message.py` lines 14-15: ```python def render(self, **kwargs: Any) -> Message: template = _inline_env.from_string(self.content_template) rendered_content = template.render(**kwargs) ```

The Jinja2 Environment is not sandboxed:

`libs/giskard-agents/src/giskard/agents/templates/environment.py` line 37: ```python _inline_env = Environment( autoescape=False, # Not SandboxedEnvironment ) ```

## Proof of Concept

```python from jinja2 import Environment env = Environment() # Same as giskard's _inline_env

# Class traversal reaches os.popen t = env.from_string("{{ ''.__class__.__mro__[1].__subclasses__() | length }}") print(t.render(…

Affected: PyPI: giskard-agents

## Summary

`ChatWorkflow.chat(message)` passes its string argument directly as a Jinja2 template source to a non-sandboxed `Environment`. A developer who passes user input to this method enables full remote code execution via Jinja2 class traversal.

The method name `chat` and parameter name `message` naturally invite passing user input directly, but the string is silently parsed as a Jinja2 template, not treated as plain text.

## Root Cause

`libs/giskard-agents/src/giskard/agents/workflow.py` line ~261: ```python def chat(self, message: str | Message | MessageTemplate, role: Role = "user") -> Self: if isinstance(message, str): message = MessageTemplate(role=role, content_template=message) ```

The string becomes `content_template`, which is parsed by `from_string()`:

`libs/giskard-agents/src/giskard/agents/templates/message.py` lines 14-15: ```python def render(self, **kwargs: Any) -> Message: template = _inline_env.from_string(self.content_template) rendered_content = template.render(**kwargs) ```

The Jinja2 Environment is not sandboxed:

`libs/giskard-agents/src/giskard/agents/templates/environment.py` line 37: ```python _inline_env = Environment( autoescape=False, # Not SandboxedEnvironment ) ```

## Proof of Concept

```python from jinja2 import Environment env = Environment() # Same as giskard's _inline_env

# Class traversal reaches os.popen t = env.from_string("{{ ''.__class__.__mro__[1].__subclasses__() | length }}") print(t.render(…