Description

CrewAI before fb2323b offers a Python blocklist approach that operates at the wrong level of abstraction, a different vulnerability than CVE-2026-2275. Import-time blocking of module names does not address the availability of Python's complete object graph. For example, calling ctypes.CDLL(None) loads the C library without relying in any import statements. In other words, a within-process sandbox cannot merely account for the import system and instead must account for the complete runtime of the Python interpreter.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "8.1",
  "pubDate": "2026-09-13T21:17:01.303Z",
  "pubdate": "2026-09-13T21:17:01.303Z",
  "executiveSummary": "CrewAI versions prior to commit fb2323b implement an ineffective security mechanism based on an import-time blocklist. This vulnerability, distinct from CVE-2026-2275, arises from a flawed abstraction layer that fails to secure the full Python object graph.\nThe vulnerability allows an attacker to bypass intended sandbox restrictions by leveraging built-in interpreter capabilities that do not rely on the import system. Because the security controls are constrained to import-time module filtering, they do not prevent direct memory access or the execution of arbitrary system-level commands through core library functions.\nThe impact includes full process compromise, as an attacker can break out of the intended execution environment to access host-level resources. Exploitation does not require elevated privileges beyond what the application itself possesses, though it does require the ability to inject or execute code within the affected process. This constitutes a high-risk security flaw as it provides a false sense of isolation for untrusted code execution.",
  "technicalDetails": "The root cause of this vulnerability is the reliance on a module-level import blocklist to enforce security boundaries. By focusing on the import system, the implementation ignores the inherent nature of the Python runtime, where the entire object graph remains accessible to any code executing within the interpreter process.\nPython's runtime environment allows access to powerful primitives that exist outside of the standard library import mechanism. Specifically, the 'ctypes' module can be utilized to load C libraries or interact directly with system memory. For instance, invoking 'ctypes.CDLL(None)' enables an attacker to load the standard C library directly from the process memory space. This action occurs without triggering any import statements that the blocklist might be configured to intercept.\nThe attack flow proceeds as follows: First, the attacker identifies that the application relies on import-based filtering to sandbox code execution. Second, the attacker crafts a payload that ignores module imports and instead interacts directly with the Python runtime's internals, such as 'ctypes' or other built-in reflection capabilities. Third, the payload is executed within the CrewAI context. Because the protection mechanism only monitors 'import' calls, it fails to inspect or block the memory-level manipulations facilitated by 'ctypes'.\nOnce the attacker successfully loads system libraries, they can execute arbitrary system calls, bypass file system restrictions, and gain full control over the execution context. This vulnerability is persistent across all versions of CrewAI before commit fb2323b. The flaw resides in the architectural decision to treat the Python import system as a security boundary rather than implementing robust, process-level isolation such as containerization, seccomp filters, or dedicated sandboxing runtimes (e.g., Pyodide or isolated sub-interpreters with strictly defined C-API access).\nBecause the runtime environment is inherently permissive once code execution is achieved, any strategy limited to blocking module names is fundamentally insufficient. This approach fails to account for the object-oriented and highly reflective nature of the Python interpreter, ultimately rendering the sandbox ineffective against even moderately skilled attackers."
}