8.3

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

Deferred
AliasesGHSA-ffg3-p8fm-mjx2PYSEC-2026-3917UBUNTU-CVE-2026-55830
Published 08-07-2026Last modified 09-07-2026

Vulnerability summary

CVE-2026-55830 is a high (CVSS 8.3) Incomplete List of Disallowed Inputs vulnerability in zopefoundation restrictedpython. EPSS estimates a 0.29% chance of exploitation in the next 30 days, higher than 21.2% of scored vulnerabilities.

Priority
Routine

Not severe (CVSS 8.3, network access); no exploitation reported by the 5 checked sources

Source freshness unavailable

How is this decided?
CVSS score
8.3/10
010
High · v3.1 (CVE.org)
EPSS score
0.29%
0%100%
Low · -0.11 pp in 30 days
KEVNot listedNot listed by any tracked catalog.
RansomwareNot flaggedNo ransomware use recorded.
Public exploits0No public exploits recorded

Advisory lineage

Upstream 0 · Downstream 0 · Related 1
CGA-FQ9M-FFJ5-VP77

Timeline

  1. 08-07-2026
    PublishedVulnerability first disclosed.
  2. 09-07-2026
    Last modifiedVulnerability information updated.

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 metrics

7 scores · 7 sources · 1 version

EPSS trend

Probability

0.29%

Chance of exploitation in the next 30 days

Percentile

21%

Versus all other CVEs

30-day change

Decrease -0.11 pp

From 0.40% on 04-10-2026

04-10-202603-11-2026

Known exploited

Compare KEV catalogs
CISA KEV

Not in the CISA KEV catalog.

ENISA CNW

Not in the ENISA CNW catalog.

CIRCL

Not in the CIRCL catalog.

Public exploits

0 found

No public exploits indexed.

Weaknesses

CWE · root cause

Affected systems

Version check

Known conditions: network-reachable, administrative account, user interaction (CVSS vector). Other conditions: not stated in public data.

Chainguard2 products
  • litellm< 1.99.0-r0
  • open-webui< 0.11.0-r9
Debian1 product
  • restrictedpythonAll versions (No fix recorded) | < 8.4-1
PyPI1 product
  • restrictedpython< 8.3
Ubuntu1 product
  • restrictedpythonAll versions (No fix recorded)
Wolfi1 product
  • open-webui< 0.11.0-r9
Zopefoundation1 product

6 vendors · 7 products

References

10 links