CVE-2026-55830

HIGHPre-NVD 8.38.3—
EchelonGraph scoreMEDIUM confidence

This high-severity CVE scores 8.3 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit probability: 0.4% (31st percentile of EPSS-scored CVEs). GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).

Triggered by: NVD CVSS baseline
Sources: epss, secondary
Elevated
8.3EG
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS PROB: 0.4%CVSS: 8.3Exploit: Elevated riskExposed services: Not assessed

A fix is available — apply it.

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 v3
8.3
EG Score
8.3HIGHmedium confidence
EG Risk
53
EG Risk 53/100CISA SSVC

EG Risk is EchelonGraph's 0–100 priority score: it fuses intrinsic severity with real-world exploitation and automatability so you can rank equal-severity CVEs and fix the most dangerous first. Higher = act sooner. Distinct from the 0–10 EG Score (severity).

How it’s computed
Severity83% × 45%
Exploitation40% × 40%
Automatability0% × 15%
CISA SSVC: Track at low, Track* at medium and Attend at high mission impact.
Action: A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.
EPSS PROB
0.4%
EPSS %ILE
32nd
KEV
Not listed

CISA SSVCTrack at low, Track* at medium and Attend at high mission impact.

A fix is available. Apply it within your standard update timelines at low or medium mission impact and sooner than that at high.

Exploitation public PoC (CISA Vulnrichment) · Automatable no (CISA Vulnrichment) · Technical impact total (CISA Vulnrichment). Mission impact is CISA's Mission & Well-being decision point, and only you can judge it: high means the affected system is essential to your organisation's mission, or its compromise could cause irreversible harm to people. CISA's decision table

Published

July 8, 2026

Last Modified

July 10, 2026

Advisory Details (2)

Auto-updated Jul 8, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github.
githubMentions a patch (unverified)🟡 PoC Available

RestrictedPython guard hooks can be shadowed via positional-only arguments · Advisory · zopefoundation/RestrictedPython · GitHub

https://github.com/zopefoundation/RestrictedPython/security/advisories/GHSA-ffg3-p8fm-mjx2
github_commit

commit 3737596ec9f2 (zopefoundation/RestrictedPython)

Fix landed in zopefoundation/RestrictedPython commit 3737596ec9f2 — awaiting tagged release

https://github.com/zopefoundation/RestrictedPython/commit/3737596ec9f28c34a073cc845bd2f4c0a80cb671

Vendor Advisories for CVE-2026-55830(1)

These vendors published their own advisory mentioning this CVE — often with vendor-specific remediation steps + affected product lists not in NVD.

Affected Packages

(4 across 4 ecosystems)
Debian:12(1)
PackageVulnerable rangeFix by version rangeDependents
restrictedpython4.0~b3-3, 6.2-1, 8.0-1, 8.1-1, 8.4-1
  • every version on: no fix on record
—
Debian:13(1)
PackageVulnerable rangeFix by version rangeDependents
restrictedpython8.0-1, 8.1-1, 8.4-1
  • every version on: no fix on record
—
Debian:14(1)
PackageVulnerable rangeFix by version rangeDependents
restrictedpython8.0-1, 8.1-1
  • every version up to 8.4-1: fixed in 8.4-1
—
PyPI(1)
PackageVulnerable rangeFix by version rangeDependents
restrictedpython3.4.2 ... 8.3a1.dev0 (44 versions)
  • every version up to 8.3: fixed in 8.3
—

Weakness Classification(1)

MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.

Data Freshness Timeline

(refreshed 7× in last 7d / 32× in last 30d)

Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.

Showing the most recent 100 of 132 total refreshes for this CVE.

  1. 2026-10-10 20:00 UTCEPSS rescore
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  1. 2026-09-16 05:15 UTCEPSS rescore
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Frequently asked(5)

What is CVE-2026-55830?
CVE-2026-55830 is a high vulnerability published on July 8, 2026. 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, checkfunctionargumentnames() rejected protected guard hook names for regular, variadic, and keyword-only arguments but omitted…
When was CVE-2026-55830 disclosed?
CVE-2026-55830 was first published on July 8, 2026, with the most recent update on July 10, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-55830 actively exploited?
CVE-2026-55830 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 0.4% probability of exploitation in the next 30 days (32nd percentile of EPSS-scored CVEs).
What is the CVSS score of CVE-2026-55830?
CVE-2026-55830 has a CVSS base score of 8.3 (a secondary CVSS source that NVD displays; NVD's own analysis pending).
How do I remediate CVE-2026-55830?
A fix for CVE-2026-55830 is available: update to the fixed version the vendor names in its advisory. The vendor advisories EchelonGraph has for CVE-2026-55830 are linked in the Vendor Advisories panel on this page.

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