CVE-2026-55830 HIGH

CVE-2026-55830: RestrictedPython guard hooks can be shadowed via positional-only arguments

Vendor Zopefoundation
Product RestrictedPython
Weakness CWE-184
Published July 8, 2026
Last update July 8, 2026

CVSS base score

8.3/10
Attack vector Network
Attack complexity Low
Privileges required High
User interaction Required
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:L

What the vulnerability does

01Description

RestrictedPython is a tool that helps to define a subset of the Python language which allows to provide a program input into a trusted environment. Prior to 8.3, check_function_argument_names() rejected protected guard hook names for regular, variadic, and keyword-only arguments but omitted positional-only arguments, allowing __getattr__, _getitem_, _write_, or _print_ to be shadowed by a local parameter and bypass the embedding application's access policy. This issue is fixed in version 8.3.

Key dates

02Disclosure timeline

July 8, 2026 CVE published