High severity · published Jul 8, 2026
CVE-2026-55830
RestrictedPython guard hooks can be shadowed via positional-only arguments
8.3
CVSS
0.3%
EPSS
No
On KEV
Description
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 vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:L
Attack vector
Network
Complexity
Low
Privileges
High
User interaction
Required
Confidentiality
High
Integrity
High
Availability
Low
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.3% · higher than 21% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RE
RestrictedPython · zopefoundation
< 8.3 · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-55830
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-55830
github.com
https://github.com/zopefoundation/RestrictedPython/commit/3737596ec9f28c34a073cc845bd2f4c0a80cb671
github.com
https://github.com/zopefoundation/RestrictedPython/security/advisories/GHSA-ffg3-p8fm-mjx2
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