MediumFix available
nltk — security advisory
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` contains a reflected cross-site scripting issue in the `lookup_...` route. A crafted `lookup_` URL can inject arbitrary HTML/JavaScript into the response page because attacker-controlled `word` data is reflected into HTML without escaping. This impacts users running the local WordNet Browser server and can lead to script execution in the browser origin of that application. Commit 1c3f799607eeb088cab2491dcf806ae83c29ad8f fixes the issue.
- Products
- nltk
- Affected versions
- 2.0~b9-0ubuntu4, 2.0~b9-0ubuntu4.1~esm2, 2.0~b9-0ubuntu4.1~esm4, 2.0~b9-0ubuntu4.1~esm5, 3.0.4-1, 3.0.5-1, 3.1-1, 3.1-1ubuntu0.1, 3.1-1ubuntu0.1+esm1, 3.1-1ubuntu0.1+esm2, 3.1-1ubuntu0.1+esm3, 3.10.0-1, 3.10.1-1, 3.10.3-1, 3.2.4-1, 3.2.5-1, 3.2.5-1ubuntu0.1, 3.2.5-1ubuntu0.1+esm1, 3.2.5-1ubuntu0.1+esm2, 3.2.5-1ubuntu0.1+esm3, 3.4.5-1, 3.4.5-2, 3.4.5-2ubuntu0.1~esm1, 3.4.5-2ubuntu0.1~esm2, 3.4.5-2ubuntu0.1~esm3, 3.5-1, 3.6.5-1, 3.6.7-1, 3.7-1, 3.7-1ubuntu0.1~esm1, 3.8.1-1, 3.8.1-1ubuntu0.1~esm1, 3.9.1-2, 3.9.1-2build1, 3.9.2-1, 3.9.2-1ubuntu0.1~esm1, 3.9.3-1
- Fixed versions
- 2.0~b9-0ubuntu4.1~esm6, 3.1-1ubuntu0.1+esm4, 3.2.5-1ubuntu0.1+esm4, 3.4.5-2ubuntu0.1~esm4, 3.7-1ubuntu0.1~esm2, 3.8.1-1ubuntu0.1~esm2, 3.9.2-1ubuntu0.1~esm2
- CVEs
- CVE-2026-33230
- Confirmed fixed CVEs
- Not specified
- Updated in this feed
- 31 Oct 2026, 02:59 UTC · Revision 1
Source evidence
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` contains a reflected cross-site scripting issue in the `lookup_...` route. A crafted `lookup_` URL can inject arbitrary HTML/JavaScript into the response page because attacker-controlled `word` data is reflected into HTML without escaping. This impacts users running the local WordNet Browser server and can lead to script execution in the browser origin of that application. Commit 1c3f799607eeb088cab2491dcf806ae83c29ad8f fixes the issue.
osv:UBUNTU-CVE-2026-33230
nltk
Fixed versions: 2.0~b9-0ubuntu4.1~esm6
nltk
Fixed versions: 3.1-1ubuntu0.1+esm4
nltk
Fixed versions: 3.2.5-1ubuntu0.1+esm4
nltk
Fixed versions: 3.4.5-2ubuntu0.1~esm4
nltk
Fixed versions: 3.7-1ubuntu0.1~esm2
nltk
Fixed versions: 3.8.1-1ubuntu0.1~esm2
nltk
Fixed versions: Not specified
nltk
Fixed versions: Not specified
nltk
Fixed versions: 3.9.2-1ubuntu0.1~esm2
Complete source record
{
"id": "03ab54e85d02a477cdb68323c136fcd3d9c4bdccbf68898db0a537a40cad9c30",
"url": "https://osv.dev/vulnerability/UBUNTU-CVE-2026-33230",
"method": "structured",
"payload": {
"kind": "advisory",
"title": "UBUNTU-CVE-2026-33230",
"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` contains a reflected cross-site scripting issue in the `lookup_...` route. A crafted `lookup_` URL can inject arbitrary HTML/JavaScript into the response page because attacker-controlled `word` data is reflected into HTML without escaping. This impacts users running the local WordNet Browser server and can lead to script execution in the browser origin of that application. Commit 1c3f799607eeb088cab2491dcf806ae83c29ad8f fixes the issue.",
"evidence": "osv:UBUNTU-CVE-2026-33230",
"products": [
{
"name": {
"value": "nltk",
"evidence": "/affected/0/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "2.0~b9-0ubuntu4.1~esm6",
"evidence": "/affected/0/ranges"
}
],
"affected_versions": [
{
"value": "2.0~b9-0ubuntu4",
"evidence": "/affected/0/versions"
},
{
"value": "2.0~b9-0ubuntu4.1~esm2",
"evidence": "/affected/0/versions"
},
{
"value": "2.0~b9-0ubuntu4.1~esm4",
"evidence": "/affected/0/versions"
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{
"value": "2.0~b9-0ubuntu4.1~esm5",
"evidence": "/affected/0/versions"
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{
"name": {
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"affected_versions": [
{
"value": "3.0.4-1",
"evidence": "/affected/1/versions"
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{
"value": "3.0.5-1",
"evidence": "/affected/1/versions"
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{
"value": "3.1-1",
"evidence": "/affected/1/versions"
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{
"value": "3.1-1ubuntu0.1",
"evidence": "/affected/1/versions"
},
{
"value": "3.1-1ubuntu0.1+esm1",
"evidence": "/affected/1/versions"
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{
"value": "3.1-1ubuntu0.1+esm2",
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{
"value": "3.1-1ubuntu0.1+esm3",
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{
"name": {
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"affected_versions": [
{
"value": "3.2.4-1",
"evidence": "/affected/2/versions"
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{
"value": "3.2.5-1",
"evidence": "/affected/2/versions"
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{
"value": "3.2.5-1ubuntu0.1",
"evidence": "/affected/2/versions"
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{
"value": "3.2.5-1ubuntu0.1+esm1",
"evidence": "/affected/2/versions"
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{
"value": "3.2.5-1ubuntu0.1+esm2",
"evidence": "/affected/2/versions"
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{
"value": "3.2.5-1ubuntu0.1+esm3",
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},
{
"name": {
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"evidence": "/affected/3/package/name"
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{
"value": "3.4.5-2ubuntu0.1~esm4",
"evidence": "/affected/3/ranges"
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],
"affected_versions": [
{
"value": "3.4.5-1",
"evidence": "/affected/3/versions"
},
{
"value": "3.4.5-2",
"evidence": "/affected/3/versions"
},
{
"value": "3.4.5-2ubuntu0.1~esm1",
"evidence": "/affected/3/versions"
},
{
"value": "3.4.5-2ubuntu0.1~esm2",
"evidence": "/affected/3/versions"
},
{
"value": "3.4.5-2ubuntu0.1~esm3",
"evidence": "/affected/3/versions"
}
]
},
{
"name": {
"value": "nltk",
"evidence": "/affected/4/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "3.7-1ubuntu0.1~esm2",
"evidence": "/affected/4/ranges"
}
],
"affected_versions": [
{
"value": "3.5-1",
"evidence": "/affected/4/versions"
},
{
"value": "3.6.5-1",
"evidence": "/affected/4/versions"
},
{
"value": "3.6.7-1",
"evidence": "/affected/4/versions"
},
{
"value": "3.7-1",
"evidence": "/affected/4/versions"
},
{
"value": "3.7-1ubuntu0.1~esm1",
"evidence": "/affected/4/versions"
}
]
},
{
"name": {
"value": "nltk",
"evidence": "/affected/5/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "3.8.1-1ubuntu0.1~esm2",
"evidence": "/affected/5/ranges"
}
],
"affected_versions": [
{
"value": "3.8.1-1",
"evidence": "/affected/5/versions"
},
{
"value": "3.8.1-1ubuntu0.1~esm1",
"evidence": "/affected/5/versions"
}
]
},
{
"name": {
"value": "nltk",
"evidence": "/affected/6/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.9.1-2",
"evidence": "/affected/6/versions"
}
]
},
{
"name": {
"value": "nltk",
"evidence": "/affected/7/package/name"
},
"prerequisites": [],
"fixed_versions": [],
"affected_versions": [
{
"value": "3.9.2-1",
"evidence": "/affected/7/versions"
},
{
"value": "3.9.3-1",
"evidence": "/affected/7/versions"
},
{
"value": "3.10.0-1",
"evidence": "/affected/7/versions"
},
{
"value": "3.10.1-1",
"evidence": "/affected/7/versions"
},
{
"value": "3.10.3-1",
"evidence": "/affected/7/versions"
}
]
},
{
"name": {
"value": "nltk",
"evidence": "/affected/8/package/name"
},
"prerequisites": [],
"fixed_versions": [
{
"value": "3.9.2-1ubuntu0.1~esm2",
"evidence": "/affected/8/ranges"
}
],
"affected_versions": [
{
"value": "3.9.1-2",
"evidence": "/affected/8/versions"
},
{
"value": "3.9.1-2build1",
"evidence": "/affected/8/versions"
},
{
"value": "3.9.2-1",
"evidence": "/affected/8/versions"
},
{
"value": "3.9.2-1ubuntu0.1~esm1",
"evidence": "/affected/8/versions"
}
]
}
],
"severity": "medium",
"structured": {
"id": "UBUNTU-CVE-2026-33230",
"aliases": [
"UBUNTU-CVE-2026-33230"
],
"metrics": [
{
"type": "CVSS_V3",
"score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"
},
{
"type": "Ubuntu",
"score": "medium"
}
],
"affected": [
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "2.0~b9-0ubuntu4.1~esm6"
}
]
}
],
"package": {
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk?arch=source&distro=esm-infra-legacy%2Ftrusty",
"ecosystem": "Ubuntu:Pro:14.04:LTS"
},
"versions": [
"2.0~b9-0ubuntu4",
"2.0~b9-0ubuntu4.1~esm2",
"2.0~b9-0ubuntu4.1~esm4",
"2.0~b9-0ubuntu4.1~esm5"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33230.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python-nltk",
"binary_version": "2.0~b9-0ubuntu4.1~esm6"
}
],
"availability": "Available with Ubuntu Pro with Legacy support add-on: https://ubuntu.com/pro"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
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{
"introduced": "0"
},
{
"fixed": "3.1-1ubuntu0.1+esm4"
}
]
}
],
"package": {
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps-legacy%2Fxenial",
"ecosystem": "Ubuntu:Pro:16.04:LTS"
},
"versions": [
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"3.0.5-1",
"3.1-1",
"3.1-1ubuntu0.1",
"3.1-1ubuntu0.1+esm1",
"3.1-1ubuntu0.1+esm2",
"3.1-1ubuntu0.1+esm3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33230.json"
},
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"binaries": [
{
"binary_name": "python-nltk",
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{
"binary_name": "python3-nltk",
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}
},
{
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],
"package": {
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fbionic",
"ecosystem": "Ubuntu:Pro:18.04:LTS"
},
"versions": [
"3.2.4-1",
"3.2.5-1",
"3.2.5-1ubuntu0.1",
"3.2.5-1ubuntu0.1+esm1",
"3.2.5-1ubuntu0.1+esm2",
"3.2.5-1ubuntu0.1+esm3"
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"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33230.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python-nltk",
"binary_version": "3.2.5-1ubuntu0.1+esm4"
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{
"binary_name": "python3-nltk",
"binary_version": "3.2.5-1ubuntu0.1+esm4"
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],
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro"
}
},
{
"ranges": [
{
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{
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},
{
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}
],
"package": {
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Ffocal",
"ecosystem": "Ubuntu:Pro:20.04:LTS"
},
"versions": [
"3.4.5-1",
"3.4.5-2",
"3.4.5-2ubuntu0.1~esm1",
"3.4.5-2ubuntu0.1~esm2",
"3.4.5-2ubuntu0.1~esm3"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33230.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-nltk",
"binary_version": "3.4.5-2ubuntu0.1~esm4"
}
],
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}
},
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{
"type": "ECOSYSTEM",
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{
"introduced": "0"
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{
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}
]
}
],
"package": {
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fjammy",
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},
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"3.5-1",
"3.6.5-1",
"3.6.7-1",
"3.7-1",
"3.7-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33230.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-nltk",
"binary_version": "3.7-1ubuntu0.1~esm2"
}
],
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro"
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
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{
"introduced": "0"
},
{
"fixed": "3.8.1-1ubuntu0.1~esm2"
}
]
}
],
"package": {
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fnoble",
"ecosystem": "Ubuntu:Pro:24.04:LTS"
},
"versions": [
"3.8.1-1",
"3.8.1-1ubuntu0.1~esm1"
],
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"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33230.json"
},
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"binaries": [
{
"binary_name": "python3-nltk",
"binary_version": "3.8.1-1ubuntu0.1~esm2"
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}
},
{
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{
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{
"introduced": "0"
}
]
}
],
"package": {
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk?arch=source&distro=questing",
"ecosystem": "Ubuntu:25.10"
},
"versions": [
"3.9.1-2"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33230.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-nltk",
"binary_version": "3.9.1-2"
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]
}
},
{
"ranges": [
{
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{
"introduced": "0"
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]
}
],
"package": {
"name": "nltk",
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"ecosystem": "Ubuntu:26.10"
},
"versions": [
"3.9.2-1",
"3.9.3-1",
"3.10.0-1",
"3.10.1-1",
"3.10.3-1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33230.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-nltk",
"binary_version": "3.10.3-1"
}
]
}
},
{
"ranges": [
{
"type": "ECOSYSTEM",
"events": [
{
"introduced": "0"
},
{
"fixed": "3.9.2-1ubuntu0.1~esm2"
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]
}
],
"package": {
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk?arch=source&distro=esm-apps%2Fresolute",
"ecosystem": "Ubuntu:Pro:26.04:LTS"
},
"versions": [
"3.9.1-2",
"3.9.1-2build1",
"3.9.2-1",
"3.9.2-1ubuntu0.1~esm1"
],
"database_specific": {
"source": "https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33230.json"
},
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-nltk",
"binary_version": "3.9.2-1ubuntu0.1~esm2"
}
],
"availability": "Available with Ubuntu Pro: https://ubuntu.com/pro"
}
}
],
"modified": "2026-10-17T12:59:59.814889317Z",
"provider": "osv",
"upstream": [
"CVE-2026-33230"
],
"references": [
"https://ubuntu.com/security/CVE-2026-33230",
"https://www.cve.org/CVERecord?id=CVE-2026-33230",
"https://github.com/nltk/nltk/commit/1c3f799607eeb088cab2491dcf806ae83c29ad8f",
"https://github.com/nltk/nltk/commit/40d0bc1d484a3458d6a63ecb5ba4957ab16ba14e",
"https://github.com/nltk/nltk/security/advisories/GHSA-gfwx-w7gr-fvh7",
"https://ubuntu.com/security/notices/USN-8302-1"
]
},
"related_cves": [
{
"value": "CVE-2026-33230",
"evidence": "/upstream"
}
],
"security_relevant": true,
"severity_evidence": "/severity/0/score"
},
"source_id": "core-osv",
"document_id": 360088,
"published_at": "2026-03-20T23:16:00+00:00"
}