CVE-2026-55830 json
RestrictedPython guard hooks can be shadowed via positional-only arguments
published 4mo ago modified 17d ago also EUVD-2026-42434 , GHSA-ffg3-p8fm-mjx2 , PYSEC-2026-3917
- cvss
- 8.3
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.3%
- EPSS 0.3% chance of exploitation in 30 days, percentile 21%
- public exploits
- 0
- none known
Summary
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.
Patch / fix
- pypi restrictedpython 8.3
- zope restrictedpython 8.3
- restrictedpython Debian 14 8.4-1
debian advisories DEBIAN-CVE-2026-55830
Is CVE-2026-55830 in your dependencies? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.
Check with FencerCISA SSVC
- Exploitation
- Proof of concept is public
- Automatable
- no
- Technical impact
- total
- Assessed
- 4mo ago
Exploit prediction
0.29% chance of exploitation in the next 30 days, higher than 21% of all scored CVEs (FIRST EPSS, 2026-11-11).
Exploits and checks
- github.com https://github.com/zopefoundation/RestrictedPython/security/advisories/GHSA-ffg3-p8fm-mjx2 referenced PoC, tagged "exploit" by a source, unverified
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 8.3 | CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:L |
| GitHub | 3.1 | 8.3 | CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:L |
| OSV | 3.1 | 8.3 | CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:H/I:H/A:L |
Affected packages
| ecosystem | package | affected | fixed in |
|---|---|---|---|
| pypi | restrictedpython | <8.3 |
8.3 |
Affected products
- zopefoundation RestrictedPython
Classification
- Weakness
-
- CWE-184 Incomplete List of Disallowed Inputs
References
-
github.com
/zopefoundation/RestrictedPython/commit/3737596ec9f28c34a073cc845bd2f4c0a80cb671
web
-
github.com
/zopefoundation/RestrictedPython/security/advisories/GHSA-ffg3-p8fm-mjx2
exploit, web, advisory
-
nvd.nist.gov
/vuln/detail/CVE-2026-55830
advisory
-
github.com
/zopefoundation/RestrictedPython
package
-
pypi.org
/project/restrictedpython
package
-
github.com
/advisories/GHSA-ffg3-p8fm-mjx2
advisory
Sources
- CVE List CVE-2026-55830
- GitHub Advisory GHSA-ffg3-p8fm-mjx2
- NVD CVE-2026-55830
- OSV PYSEC-2026-3917
- Maintainer advisory GHSA-ffg3-p8fm-mjx2
Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.
The maintainers of zopefoundation/RestrictedPython published their own advisory on GitHub. Reviewed sources take precedence over it.
CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.