High 8.3Published Jul 8, 2026

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

Updated under an hour ago (Oct 26, 2026, 4:20 PM ET)

Does this affect you?

It affects zopefoundation RestrictedPython. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for zopefoundation RestrictedPython

Exploited in the last 30 days

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.

CVSS: 8.3 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:L
Weakness (CWE): CWE-184
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: GitHub_M
NVD analysis: Deferred
Record last updated: Jul 9, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

zopefoundation RestrictedPython zopefoundation:restrictedpython (from the name)	before 8.3	CNA record

References

References

https://github.com/zopefoundation/RestrictedPython/security/advisories/GHSA-ffg3-p8fm-mjx2	x-refsource-confirm
https://github.com/zopefoundation/RestrictedPython/commit/3737596ec9f28c34a073cc845bd2f4c0a80cb671	x-refsource-misc

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.