NVD / CVE Program· CNA GitHub_M

CVE-2026-33231: NLTK has unauthenticated remote shutdown in nltk.app.wordnet_app

Noroxi assessment

Priority: Monitor (action score 30/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 1.2% (FIRST EPSS); higher than 68.9% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
According to CISA the attack is automatable: targets can be found by mass scanning.
Fixed version: nltk (Debian:14) 3.10.0-1; nltk (PyPI) 3.9.4.

Low priority for now. Upgrade to nltk (Debian:14) 3.10.0-1; nltk (PyPI) 3.9.4 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.5 · v3.1—No exploit Fix available

Published: Mar 20, 2026
Updated: Sep 9, 2026
EPSS: 1.2% · 68th percentile
CWE: CWE-306

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 1.2%

CISA SSVC decision

Exploitation: proof of concept
Automatable: yes
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · GitHub_M: 7.5; NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
nltk	nltk	cpe:2.3:a:nltk:nltk

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

nltk nltkup to 3.9.3 inclusive

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

nltk nltk
- <= 3.9.3affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	nltk	from 0	—
Debian:14	nltk	before 3.10.0-1	3.10.0-1
PyPI	nltk	before 3.9.4	3.9.4

Same product

nltk: all records

Other highest-scoring records for the same primary product.

CVE-2026-0848Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading
40Plan
CVE-2026-79675NLTK before 3.10.3 JVM Argument Injection via Per-Call Options
37Monitor
CVE-2026-79657NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization
37Monitor

Published before and after this one in the same product

← EarlierCVE-2026-0846Mar 9, 2026 · Arbitrary File Read via Absolute Path Input in nltk.util.filestring()
30Monitor
← EarlierCVE-2026-33230Mar 20, 2026 · nltk Vulnerable to Cross-site Scripting
24Monitor
Later →CVE-2026-33236Mar 20, 2026 · NLTK has a Downloader Path Traversal Vulnerability (AFO) - Arbitrary File Overwrite
32Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
debian:nltk	3.10.0-1 · Debian:14	Package registry (OSV)
PyPI:nltk	3.9.4	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

nltk/nltkcommit bbaae83

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

—

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

CVE-2025-1400930 days apartZip Slip Vulnerability in nltk/nltk Leading to Remote Code Execution
35Monitor
CVE-2025-71408126 days apartNLTK < 3.9.3 Eval Injection via collocations.py Command-Line Arguments
34Monitor
CVE-2026-78680158 days apartNLTK before 3.10.3 Arbitrary Code Execution via Graphviz dot Binary
34Monitor
CVE-2026-62383155 days apartnltk IPIPANCorpusReader Symlink Arbitrary File Read
27Monitor

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: none
Integrity: none
Availability: high · the service can be disrupted

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: None
Integrity impact: None
Availability impact: High

Weakness class (CWE)

CWE-306 · Missing Authentication for Critical Function

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

nvd-secondary

Root cause

A function added for development or support ships to production without authentication. It often relies on the assumption that it is “only reachable from the internal network.”

The bug in code

The whole CWE-306 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1// Added for the support team
2app.post("/maintenance/reset", resetDevice);

Fixed

1if (config.maintenanceEnabled) {
2  app.post(
3    "/maintenance/reset",
4    requireSession, requireRole("admin"), resetDevice
5  );
6}

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

—

Change log

Fix✗ → ✓Sep 28, 2026, 10:45 PM UTC

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References

github.com/nltk/nltk/commit/bbaae83db86a0f49e00f5b0db44a7254c268de9b

Show all references (7 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

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