CVE-2026-33231

HIGHPre-NVD 7.57.5
EchelonGraph scoreLOW confidence

This high-severity CVE scores 7.5 under a secondary CVSS source (NVD's own analysis pending). EPSS exploit-prediction score not yet available (the EPSS model rescores nightly; freshly-published CVEs typically appear within 48 hours). 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: secondary
7.5
EchelonGraph verdictPlan a fixSerious severity, but no confirmed exploitation yet.
  • High severity, but no confirmed exploitation yet
CISA-KEV: Not listedEPSS: 1%CVSS: 7.5Exploit: NoneExposed: 0

A fix is available — apply it.

NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. In versions 3.9.3 and prior, nltk.app.wordnet_app allows unauthenticated remote shutdown of the local WordNet Browser HTTP server when it is started in its default mode. A simple GET /SHUTDOWN%20THE%20SERVER request causes the process to terminate immediately via os._exit(0), resulting in a denial of service. Commit bbaae83db86a0f49e00f5b0db44a7254c268de9b patches the issue.

CVSS v3
7.5
EG Score
7.5(low)
EPSS
53.9%
KEV
Not listed

Published

March 20, 2026

Last Modified

June 30, 2026

Advisory Details (7)

Auto-updated Jul 6, 2026
🔬 Proof of concept available. Patch available. Sources: github_commit, github, redhat.
redhat
https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33231.json
redhat

2449836 – (CVE-2026-33231) CVE-2026-33231 nltk: NLTK: Denial of Service via unauthenticated remote shutdown

https://bugzilla.redhat.com/show_bug.cgi?id=2449836
redhat Patch Available

cve-details

https://access.redhat.com/security/cve/CVE-2026-33231
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:24977
redhat Patch Available
https://access.redhat.com/errata/RHSA-2026:19712
github Patch Available🟡 PoC Available

Unauthenticated remote shutdown in nltk.app.wordnet_app · Advisory · nltk/nltk · GitHub

https://github.com/nltk/nltk/security/advisories/GHSA-jm6w-m3j8-898g
github_commit Patch Available

commit bbaae83db86a (nltk/nltk)

Patch available: nltk/nltk v3.10.0-rc1 (contains commit bbaae83db86a)

https://github.com/nltk/nltk/commit/bbaae83db86a0f49e00f5b0db44a7254c268de9b

Vendor Advisories for CVE-2026-33231(2)

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

Patch Availability(3)

Vendor / EcosystemFixed in / PatchReleasedSource
ubuntupython-nltk (2.0~b9-0ubuntu4.1~esm6) @ trusty2026-06-30ubuntu
redhatrhoai/odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9:17800692262026-06-10redhat
redhatrhoai/odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9:17782630542026-05-20redhat

Patches are aggregated from vendor advisories (Red Hat, Microsoft, Cisco, GitHub) and package ecosystems (OSV, GHSA). Multiple rows for the same upstream release have been deduplicated.

Affected Packages

(1 across 1 ecosystem)
PyPI(1)
PackageVulnerable rangeFixed inDependents
nltk0.8 ... 3.9b1 (64 versions)3.9.4—

Weakness Classification(1)

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

Additional Vendor Advisories

(1)

Vendors that published advisories for this CVE beyond the curated set above. Broader coverage but minimal per-row detail — click through for the original advisory.

Data Freshness Timeline

(refreshed 8× in last 7d / 11× 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.

  1. 2026-07-06 16:27 UTCEPSS rescore
  2. 2026-07-06 16:27 UTCEPSS rescore
  3. 2026-07-06 02:23 UTCEPSS rescore
  4. 2026-07-06 02:23 UTCEPSS rescore
  5. 2026-07-05 02:30 UTCEPSS rescore
  6. 2026-07-04 06:31 UTCEPSS rescore
  7. 2026-07-01 15:06 UTCEPSS rescore
  8. 2026-06-30 23:22 UTCEPSS rescore
  9. 2026-06-30 04:37 UTCEG score recompute
  10. 2026-06-30 04:37 UTCVendor advisory
  11. 2026-06-30 04:32 UTCNVD updatefirst tracked

Related CVEs(same vendor + same CWE)

Frequently asked(5)

What is CVE-2026-33231?
CVE-2026-33231 is a high vulnerability published on March 20, 2026. NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. In versions 3.9.3 and prior, nltk.app.wordnetapp allows unauthenticated remote shutdown of the local WordNet Browser HTTP server…
When was CVE-2026-33231 disclosed?
CVE-2026-33231 was first published in the National Vulnerability Database on March 20, 2026, with the most recent update on June 30, 2026. EchelonGraph re-ingests CVE updates from NVD on a 2-hour cycle, so this page reflects the latest published state.
Is CVE-2026-33231 actively exploited?
CVE-2026-33231 is not currently on CISA's Known Exploited Vulnerabilities catalog. FIRST EPSS estimates a 53.9% percentile likelihood of exploitation in the next 30 days — higher percentiles indicate greater predicted risk.
What is the CVSS score of CVE-2026-33231?
CVE-2026-33231 has a CVSS v3 base score of 7.5 (NVD). The EG score is currently aggregating — additional source signals are being incorporated as they become available..
How do I remediate CVE-2026-33231?
Patch to the fixed version published by the affected vendor. Where vendor advisories exist for CVE-2026-33231, EchelonGraph cross-links them in the Vendor Advisories panel below — those typically contain the canonical remediation steps, fixed version numbers, and any vendor-specific mitigations.

Dependency Blast Radius

See which npm, PyPI, Go, and Maven packages are affected by CVE-2026-33231

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