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The vulnerability arises from an incomplete AST-based blocklist in PySpector’s PluginSecurity.validate_plugin_code. The validator maintains a set `fatal_calls` that explicitly forbids dangerous identifiers like eval, exec, os.system, and subprocess.Popen. This exhaustive blocklist approach is inherently incomplete. Multiple Python constructs are not checked, allowing an attacker who can supply a plugin file to bypass validation and achieve arbitrary code execution within the PySpector process.
Key bypass techniques not detected:
– `importlib.import_module` is absent from fatal_calls; it can load os, subprocess, or any module at runtime.
– Dynamic attribute chains using `__class__.__mro__` traverse class hierarchies to reach built‑in functions without naming them directly.
– `ctypes` is not blocked and can call native library functions (e.g., ctypes.CDLL(None).system).
– `__builtins__` dictionary access exposes all built‑in callables (e.g., __builtins__['eval']).
– `types.CodeType` allows construction and execution of raw code objects.
– Alias resolution only handles simple import X as Y; aliased imports of blocked modules evade detection, as do transitive imports through unblocked modules.
Because the validator gates plugin installation with the `–trust` flag, a successful bypass causes untrusted plugin code to run with full privileges of the PySpector process. The provided Proof of Concept uses `importlib.import_module(‘os’)` followed by `mod.system(‘id > /tmp/pwned’)` to write a file. The validation passes, and the code executes.
DailyCVE form:
Platform: PySpector
Version: All versions
Vulnerability: Plugin security bypass
Severity: Critical
date: 2026-04-16
Prediction: Not disclosed
What Undercode Say:
Simulate the vulnerable validation and exploit
python3 -c "
import textwrap, tempfile, os
evil = textwrap.dedent(\"\"\"
import importlib
mod = importlib.import_module('os')
mod.system('id > /tmp/pwned')
\"\"\")
with tempfile.NamedTemporaryFile(suffix='.py', mode='w', delete=False) as f:
f.write(evil)
path = f.name
from pyspector.plugin_system import PluginSecurity
print('Validation passed:', PluginSecurity.validate_plugin_code(path))
exec(compile(open(path).read(), path, 'exec'))
print(open('/tmp/pwned').read())
os.unlink(path)
"
Alternative bypass using ctypes
import ctypes
ctypes.CDLL(None).system("id > /tmp/pwned2")
Exploit:
Supply a plugin file containing any unblocked import (e.g., import importlib; importlib.import_module('os').system('cmd')) or use __builtins__['eval']('__import__("os").system("cmd")'). Install the plugin with `–trust` flag; validation passes, code executes.
Protection from this CVE:
Replace blocklist with allowlist of safe operations. Use a sandbox (e.g., pysandbox, nsjail, or container isolation). Disable dynamic imports and dunder attribute access via AST rewriting. Reject plugins unless cryptographically signed from a trusted source.
Impact:
Arbitrary OS command execution with privileges of PySpector process. Full system compromise, data exfiltration, or lateral movement. The static analysis provides false security, affecting all versions with the plugin system.
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Sources:
Reported By: github.com
Extra Source Hub:
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