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CVE-2026-63310 (GCVE-0-2026-63310)
Vulnerability from cvelistv5 – Published: 2026-08-22 14:12 – Updated: 2026-09-14 23:10
VLAI
EPSS
VEX
This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.
Show details on NVD website{
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"status": "final",
"title": "nltk: NLTK before 3.9.3 Missing Post-Download Integrity Verification",
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brew-acronym-cve-2026-63310
Vulnerability from osv_homebrew
Published
2026-09-02 08:43
Modified
2026-09-17 18:47
Summary
NLTK: Missing Post-Download Integrity Verification Allows Malicious Package Injection
Details
NLTK's package downloader in nltk/downloader.py does not verify file integrity after download and before extraction.
The download flow at lines 789-825: 1. File is downloaded to a temp path via HTTP 2. os.replace(tmp_filepath, filepath) moves it to the final location (line 799) 3. Extraction begins via _unzip_iter() (line 825)
Between steps 2 and 3, there is no SHA-256 verification. The checksum logic exists in _pkg_status() (lines 982-1015) but it is only used BEFORE download as a status check ("is this package already installed and up-to-date?"). It is never called after download to verify the file that was actually received.
Attack vectors: 1. MITM during HTTP download (NLTK downloads from http:// by default on some mirrors) 2. Race condition on shared filesystems (attacker replaces file between os.replace and _unzip_iter) 3. DNS poisoning redirecting to attacker-controlled server
PoC:
import nltk
import unittest.mock
import zipfile
import io
import os
# Create a malicious zip that will be "downloaded"
malicious_zip = io.BytesIO()
with zipfile.ZipFile(malicious_zip, 'w') as zf:
zf.writestr('punkt_tab/tokenizers/punkt_tab/english.pickle',
b'MALICIOUS PAYLOAD - attacker controlled content')
# Patch urllib to return our malicious zip
with unittest.mock.patch('urllib.request.urlopen') as mock_urlopen:
mock_response = unittest.mock.MagicMock()
mock_response.read.return_value = malicious_zip.getvalue()
mock_response.headers = {'Content-Length': str(len(malicious_zip.getvalue()))}
mock_urlopen.return_value = mock_response
# Download proceeds, no integrity check catches the swap
# nltk.download('punkt_tab') # Would install attacker payload
This is distinct from CVE-2024-39705 (pickle deserialization via download) and CVE-2025-14009 (zip-slip path traversal). Those address what happens AFTER extraction. This finding addresses the gap BEFORE extraction where integrity is never verified.
Suggested fix: After os.replace() and before _unzip_iter(), compute SHA-256 of the final file and compare against the expected checksum from the package index. Reject and delete the file if the hash does not match.
Severity
5.3 (Medium)
References
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "nltk",
"resource_purl": "pkg:pypi/nltk@3.10.3",
"upstream_fixed_in": "3.9.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "acronym",
"purl": "pkg:brew/acronym"
},
"ranges": [
{
"events": [
{
"introduced": "2.0.0"
},
{
"fixed": "2.0.0_2"
}
],
"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": "NLTK\u0027s package downloader in nltk/downloader.py does not verify file integrity after download and before extraction.\n\nThe download flow at lines 789-825:\n1. File is downloaded to a temp path via HTTP\n2. os.replace(tmp_filepath, filepath) moves it to the final location (line 799)\n3. Extraction begins via _unzip_iter() (line 825)\n\nBetween steps 2 and 3, there is no SHA-256 verification. The checksum logic exists in _pkg_status() (lines 982-1015) but it is only used BEFORE download as a status check (\"is this package already installed and up-to-date?\"). It is never called after download to verify the file that was actually received.\n\nAttack vectors:\n1. MITM during HTTP download (NLTK downloads from http:// by default on some mirrors)\n2. Race condition on shared filesystems (attacker replaces file between os.replace and _unzip_iter)\n3. DNS poisoning redirecting to attacker-controlled server\n\nPoC:\n```python\nimport nltk\nimport unittest.mock\nimport zipfile\nimport io\nimport os\n\n# Create a malicious zip that will be \"downloaded\"\nmalicious_zip = io.BytesIO()\nwith zipfile.ZipFile(malicious_zip, \u0027w\u0027) as zf:\n zf.writestr(\u0027punkt_tab/tokenizers/punkt_tab/english.pickle\u0027, \n b\u0027MALICIOUS PAYLOAD - attacker controlled content\u0027)\n\n# Patch urllib to return our malicious zip\nwith unittest.mock.patch(\u0027urllib.request.urlopen\u0027) as mock_urlopen:\n mock_response = unittest.mock.MagicMock()\n mock_response.read.return_value = malicious_zip.getvalue()\n mock_response.headers = {\u0027Content-Length\u0027: str(len(malicious_zip.getvalue()))}\n mock_urlopen.return_value = mock_response\n \n # Download proceeds, no integrity check catches the swap\n # nltk.download(\u0027punkt_tab\u0027) # Would install attacker payload\n```\n\nThis is distinct from CVE-2024-39705 (pickle deserialization via download) and CVE-2025-14009 (zip-slip path traversal). Those address what happens AFTER extraction. This finding addresses the gap BEFORE extraction where integrity is never verified.\n\nSuggested fix: After os.replace() and before _unzip_iter(), compute SHA-256 of the final file and compare against the expected checksum from the package index. Reject and delete the file if the hash does not match.",
"id": "BREW-acronym-CVE-2026-63310",
"modified": "2026-09-17T18:47:55Z",
"published": "2026-09-02T08:43:54Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-5wp5-5229-5g6q"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-12259"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/pull/3449"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/commit/0e26734a61094b628d93e26dc18dd7302567ac46"
},
{
"type": "PACKAGE",
"url": "https://github.com/nltk/nltk"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/releases/tag/3.9.3"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3729.yaml"
},
{
"type": "WEB",
"url": "https://huntr.com/bounties/659ccf6d-12d4-4d4a-84c0-078633c35a5d"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/nltk-before-missing-post-download-integrity-verification"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "NLTK: Missing Post-Download Integrity Verification Allows Malicious Package Injection",
"upstream": [
"PYSEC-2026-3729",
"CVE-2026-63310",
"GHSA-5wp5-5229-5g6q",
"CVE-2026-12259",
"GHSA-gf32-cmjh-8m9v"
]
}
brew-gptline-cve-2026-63310
Vulnerability from osv_homebrew
Published
2026-09-02 09:04
Modified
2026-09-17 19:32
Summary
NLTK: Missing Post-Download Integrity Verification Allows Malicious Package Injection
Details
NLTK's package downloader in nltk/downloader.py does not verify file integrity after download and before extraction.
The download flow at lines 789-825: 1. File is downloaded to a temp path via HTTP 2. os.replace(tmp_filepath, filepath) moves it to the final location (line 799) 3. Extraction begins via _unzip_iter() (line 825)
Between steps 2 and 3, there is no SHA-256 verification. The checksum logic exists in _pkg_status() (lines 982-1015) but it is only used BEFORE download as a status check ("is this package already installed and up-to-date?"). It is never called after download to verify the file that was actually received.
Attack vectors: 1. MITM during HTTP download (NLTK downloads from http:// by default on some mirrors) 2. Race condition on shared filesystems (attacker replaces file between os.replace and _unzip_iter) 3. DNS poisoning redirecting to attacker-controlled server
PoC:
import nltk
import unittest.mock
import zipfile
import io
import os
# Create a malicious zip that will be "downloaded"
malicious_zip = io.BytesIO()
with zipfile.ZipFile(malicious_zip, 'w') as zf:
zf.writestr('punkt_tab/tokenizers/punkt_tab/english.pickle',
b'MALICIOUS PAYLOAD - attacker controlled content')
# Patch urllib to return our malicious zip
with unittest.mock.patch('urllib.request.urlopen') as mock_urlopen:
mock_response = unittest.mock.MagicMock()
mock_response.read.return_value = malicious_zip.getvalue()
mock_response.headers = {'Content-Length': str(len(malicious_zip.getvalue()))}
mock_urlopen.return_value = mock_response
# Download proceeds, no integrity check catches the swap
# nltk.download('punkt_tab') # Would install attacker payload
This is distinct from CVE-2024-39705 (pickle deserialization via download) and CVE-2025-14009 (zip-slip path traversal). Those address what happens AFTER extraction. This finding addresses the gap BEFORE extraction where integrity is never verified.
Suggested fix: After os.replace() and before _unzip_iter(), compute SHA-256 of the final file and compare against the expected checksum from the package index. Reject and delete the file if the hash does not match.
Severity
5.3 (Medium)
References
| URL | Type | ||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "nltk",
"resource_purl": "pkg:pypi/nltk@3.10.3",
"upstream_fixed_in": "3.9.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "gptline",
"purl": "pkg:brew/gptline"
},
"ranges": [
{
"events": [
{
"introduced": "1.0.8"
},
{
"fixed": "1.0.8_14"
}
],
"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": "NLTK\u0027s package downloader in nltk/downloader.py does not verify file integrity after download and before extraction.\n\nThe download flow at lines 789-825:\n1. File is downloaded to a temp path via HTTP\n2. os.replace(tmp_filepath, filepath) moves it to the final location (line 799)\n3. Extraction begins via _unzip_iter() (line 825)\n\nBetween steps 2 and 3, there is no SHA-256 verification. The checksum logic exists in _pkg_status() (lines 982-1015) but it is only used BEFORE download as a status check (\"is this package already installed and up-to-date?\"). It is never called after download to verify the file that was actually received.\n\nAttack vectors:\n1. MITM during HTTP download (NLTK downloads from http:// by default on some mirrors)\n2. Race condition on shared filesystems (attacker replaces file between os.replace and _unzip_iter)\n3. DNS poisoning redirecting to attacker-controlled server\n\nPoC:\n```python\nimport nltk\nimport unittest.mock\nimport zipfile\nimport io\nimport os\n\n# Create a malicious zip that will be \"downloaded\"\nmalicious_zip = io.BytesIO()\nwith zipfile.ZipFile(malicious_zip, \u0027w\u0027) as zf:\n zf.writestr(\u0027punkt_tab/tokenizers/punkt_tab/english.pickle\u0027, \n b\u0027MALICIOUS PAYLOAD - attacker controlled content\u0027)\n\n# Patch urllib to return our malicious zip\nwith unittest.mock.patch(\u0027urllib.request.urlopen\u0027) as mock_urlopen:\n mock_response = unittest.mock.MagicMock()\n mock_response.read.return_value = malicious_zip.getvalue()\n mock_response.headers = {\u0027Content-Length\u0027: str(len(malicious_zip.getvalue()))}\n mock_urlopen.return_value = mock_response\n \n # Download proceeds, no integrity check catches the swap\n # nltk.download(\u0027punkt_tab\u0027) # Would install attacker payload\n```\n\nThis is distinct from CVE-2024-39705 (pickle deserialization via download) and CVE-2025-14009 (zip-slip path traversal). Those address what happens AFTER extraction. This finding addresses the gap BEFORE extraction where integrity is never verified.\n\nSuggested fix: After os.replace() and before _unzip_iter(), compute SHA-256 of the final file and compare against the expected checksum from the package index. Reject and delete the file if the hash does not match.",
"id": "BREW-gptline-CVE-2026-63310",
"modified": "2026-09-17T19:32:01Z",
"published": "2026-09-02T09:04:32Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-5wp5-5229-5g6q"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-12259"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/pull/3449"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/commit/0e26734a61094b628d93e26dc18dd7302567ac46"
},
{
"type": "PACKAGE",
"url": "https://github.com/nltk/nltk"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/releases/tag/3.9.3"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3729.yaml"
},
{
"type": "WEB",
"url": "https://huntr.com/bounties/659ccf6d-12d4-4d4a-84c0-078633c35a5d"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/nltk-before-missing-post-download-integrity-verification"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "NLTK: Missing Post-Download Integrity Verification Allows Malicious Package Injection",
"upstream": [
"PYSEC-2026-3729",
"CVE-2026-63310",
"GHSA-5wp5-5229-5g6q",
"CVE-2026-12259",
"GHSA-gf32-cmjh-8m9v"
]
}
brew-safety-cve-2026-63310
Vulnerability from osv_homebrew
Published
2026-09-02 09:53
Modified
2026-09-17 17:35
Summary
NLTK: Missing Post-Download Integrity Verification Allows Malicious Package Injection
Details
NLTK's package downloader in nltk/downloader.py does not verify file integrity after download and before extraction.
The download flow at lines 789-825: 1. File is downloaded to a temp path via HTTP 2. os.replace(tmp_filepath, filepath) moves it to the final location (line 799) 3. Extraction begins via _unzip_iter() (line 825)
Between steps 2 and 3, there is no SHA-256 verification. The checksum logic exists in _pkg_status() (lines 982-1015) but it is only used BEFORE download as a status check ("is this package already installed and up-to-date?"). It is never called after download to verify the file that was actually received.
Attack vectors: 1. MITM during HTTP download (NLTK downloads from http:// by default on some mirrors) 2. Race condition on shared filesystems (attacker replaces file between os.replace and _unzip_iter) 3. DNS poisoning redirecting to attacker-controlled server
PoC:
import nltk
import unittest.mock
import zipfile
import io
import os
# Create a malicious zip that will be "downloaded"
malicious_zip = io.BytesIO()
with zipfile.ZipFile(malicious_zip, 'w') as zf:
zf.writestr('punkt_tab/tokenizers/punkt_tab/english.pickle',
b'MALICIOUS PAYLOAD - attacker controlled content')
# Patch urllib to return our malicious zip
with unittest.mock.patch('urllib.request.urlopen') as mock_urlopen:
mock_response = unittest.mock.MagicMock()
mock_response.read.return_value = malicious_zip.getvalue()
mock_response.headers = {'Content-Length': str(len(malicious_zip.getvalue()))}
mock_urlopen.return_value = mock_response
# Download proceeds, no integrity check catches the swap
# nltk.download('punkt_tab') # Would install attacker payload
This is distinct from CVE-2024-39705 (pickle deserialization via download) and CVE-2025-14009 (zip-slip path traversal). Those address what happens AFTER extraction. This finding addresses the gap BEFORE extraction where integrity is never verified.
Suggested fix: After os.replace() and before _unzip_iter(), compute SHA-256 of the final file and compare against the expected checksum from the package index. Reject and delete the file if the hash does not match.
Severity
5.3 (Medium)
References
| URL | Type | ||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"fix": "bump",
"range_state": "fixed",
"resource": "nltk",
"resource_purl": "pkg:pypi/nltk@3.10.3",
"upstream_fixed_in": "3.9.3"
},
"package": {
"ecosystem": "Homebrew",
"name": "safety",
"purl": "pkg:brew/safety"
},
"ranges": [
{
"events": [
{
"introduced": "3.3.1"
},
{
"fixed": "3.7.0_5"
}
],
"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": "NLTK\u0027s package downloader in nltk/downloader.py does not verify file integrity after download and before extraction.\n\nThe download flow at lines 789-825:\n1. File is downloaded to a temp path via HTTP\n2. os.replace(tmp_filepath, filepath) moves it to the final location (line 799)\n3. Extraction begins via _unzip_iter() (line 825)\n\nBetween steps 2 and 3, there is no SHA-256 verification. The checksum logic exists in _pkg_status() (lines 982-1015) but it is only used BEFORE download as a status check (\"is this package already installed and up-to-date?\"). It is never called after download to verify the file that was actually received.\n\nAttack vectors:\n1. MITM during HTTP download (NLTK downloads from http:// by default on some mirrors)\n2. Race condition on shared filesystems (attacker replaces file between os.replace and _unzip_iter)\n3. DNS poisoning redirecting to attacker-controlled server\n\nPoC:\n```python\nimport nltk\nimport unittest.mock\nimport zipfile\nimport io\nimport os\n\n# Create a malicious zip that will be \"downloaded\"\nmalicious_zip = io.BytesIO()\nwith zipfile.ZipFile(malicious_zip, \u0027w\u0027) as zf:\n zf.writestr(\u0027punkt_tab/tokenizers/punkt_tab/english.pickle\u0027, \n b\u0027MALICIOUS PAYLOAD - attacker controlled content\u0027)\n\n# Patch urllib to return our malicious zip\nwith unittest.mock.patch(\u0027urllib.request.urlopen\u0027) as mock_urlopen:\n mock_response = unittest.mock.MagicMock()\n mock_response.read.return_value = malicious_zip.getvalue()\n mock_response.headers = {\u0027Content-Length\u0027: str(len(malicious_zip.getvalue()))}\n mock_urlopen.return_value = mock_response\n \n # Download proceeds, no integrity check catches the swap\n # nltk.download(\u0027punkt_tab\u0027) # Would install attacker payload\n```\n\nThis is distinct from CVE-2024-39705 (pickle deserialization via download) and CVE-2025-14009 (zip-slip path traversal). Those address what happens AFTER extraction. This finding addresses the gap BEFORE extraction where integrity is never verified.\n\nSuggested fix: After os.replace() and before _unzip_iter(), compute SHA-256 of the final file and compare against the expected checksum from the package index. Reject and delete the file if the hash does not match.",
"id": "BREW-safety-CVE-2026-63310",
"modified": "2026-09-17T17:35:56Z",
"published": "2026-09-02T09:53:14Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-5wp5-5229-5g6q"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-12259"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/pull/3449"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/commit/0e26734a61094b628d93e26dc18dd7302567ac46"
},
{
"type": "PACKAGE",
"url": "https://github.com/nltk/nltk"
},
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/releases/tag/3.9.3"
},
{
"type": "WEB",
"url": "https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-3729.yaml"
},
{
"type": "WEB",
"url": "https://huntr.com/bounties/659ccf6d-12d4-4d4a-84c0-078633c35a5d"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/nltk-before-missing-post-download-integrity-verification"
}
],
"schema_version": "1.7.3",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:N/I:H/A:N",
"type": "CVSS_V3"
}
],
"summary": "NLTK: Missing Post-Download Integrity Verification Allows Malicious Package Injection",
"upstream": [
"PYSEC-2026-3729",
"CVE-2026-63310",
"GHSA-5wp5-5229-5g6q",
"CVE-2026-12259",
"GHSA-gf32-cmjh-8m9v"
]
}
FKIE_CVE-2026-63310
Vulnerability from fkie_nvd - Published: 2026-08-22 15:16 - Updated: 2026-09-15 00:16
Severity
Summary
Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.
References
| URL | Tags |
|---|
Impacted products
| Vendor | Product | Version |
|---|
{
"cveTags": [],
"descriptions": [
{
"lang": "en",
"value": "Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority."
}
],
"id": "CVE-2026-63310",
"lastModified": "2026-09-15T00:16:57.827",
"metrics": {},
"published": "2026-08-22T15:16:19.100",
"references": [],
"sourceIdentifier": "disclosure@vulncheck.com",
"vulnStatus": "Rejected"
}
GHSA-GF32-CMJH-8M9V
Vulnerability from github – Published: 2026-08-22 15:31 – Updated: 2026-09-09 16:33
Withdrawn 2026-09-09
VLAI
Summary
Duplicate Advisory: NLTK: Missing Post-Download Integrity Verification Allows Malicious Package Injection
Details
Duplicate Advisory
This advisory has been withdrawn because it is a duplicate of GHSA-5wp5-5229-5g6q. This link is maintained to preserve external references.
Original Description
NLTK before 3.9.3 fails to verify file integrity after downloading packages and before extraction in the downloader module. Attackers can perform man-in-the-middle attacks or DNS poisoning to inject malicious package contents that are extracted without validation.
Severity
7.1 (High)
{
"affected": [
{
"package": {
"ecosystem": "PyPI",
"name": "nltk"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"last_affected": "3.9.2"
}
],
"type": "ECOSYSTEM"
}
]
}
],
"aliases": [
"CVE-2026-63310"
],
"database_specific": {
"cwe_ids": [
"CWE-494"
],
"github_reviewed": true,
"github_reviewed_at": "2026-09-09T16:33:54Z",
"nvd_published_at": "2026-08-22T15:16:19Z",
"severity": "CRITICAL"
},
"details": "## Duplicate Advisory\n\nThis advisory has been withdrawn because it is a duplicate of\u00a0GHSA-5wp5-5229-5g6q. This link is maintained to preserve external references.\n\n## Original Description\nNLTK before 3.9.3 fails to verify file integrity after downloading packages and before extraction in the downloader module. Attackers can perform man-in-the-middle attacks or DNS poisoning to inject malicious package contents that are extracted without validation.",
"id": "GHSA-gf32-cmjh-8m9v",
"modified": "2026-09-09T16:33:54Z",
"published": "2026-08-22T15:31:03Z",
"references": [
{
"type": "WEB",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-5wp5-5229-5g6q"
},
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-63310"
},
{
"type": "WEB",
"url": "https://www.vulncheck.com/advisories/nltk-before-missing-post-download-integrity-verification"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
"type": "CVSS_V4"
}
],
"summary": "Duplicate Advisory: NLTK: Missing Post-Download Integrity Verification Allows Malicious Package Injection",
"withdrawn": "2026-09-09T16:33:54Z"
}
PYSEC-2026-3729
Vulnerability from pysec - Published: 2026-08-22 15:16 - Updated: 2026-09-10 10:07
VLAI
Details
NLTK before 3.9.3 fails to verify file integrity after downloading packages and before extraction in the downloader module. Attackers can perform man-in-the-middle attacks or DNS poisoning to inject malicious package contents that are extracted without validation.
Severity
6.5 (Medium)
Impacted products
| Name | purl | nltk | pkg:pypi/nltk |
|---|
{
"affected": [
{
"ecosystem_specific": {},
"package": {
"ecosystem": "PyPI",
"name": "nltk",
"purl": "pkg:pypi/nltk"
},
"ranges": [
{
"events": [
{
"introduced": "0"
},
{
"fixed": "3.9.3"
}
],
"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",
"3.9b1"
]
}
],
"aliases": [
"CVE-2026-63310",
"GHSA-5wp5-5229-5g6q",
"GHSA-gf32-cmjh-8m9v"
],
"details": "NLTK before 3.9.3 fails to verify file integrity after downloading packages and before extraction in the downloader module. Attackers can perform man-in-the-middle attacks or DNS poisoning to inject malicious package contents that are extracted without validation.",
"id": "PYSEC-2026-3729",
"modified": "2026-09-10T10:07:34.051223Z",
"published": "2026-08-22T15:16:19.100Z",
"references": [
{
"type": "ADVISORY",
"url": "https://www.vulncheck.com/advisories/nltk-before-missing-post-download-integrity-verification"
},
{
"type": "EVIDENCE",
"url": "https://github.com/nltk/nltk/security/advisories/GHSA-5wp5-5229-5g6q"
},
{
"type": "ADVISORY",
"url": "https://github.com/advisories/GHSA-5wp5-5229-5g6q"
}
],
"severity": [
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N",
"type": "CVSS_V3"
}
]
}
ubuntu-cve-2026-63310 Withdrawn 2026-09-16
Vulnerability from osv_ubuntu
Published
2026-08-22 15:16
Modified
2026-09-02 16:20
Summary
Details
NLTK before 3.9.3 fails to verify file integrity after downloading packages and before extraction in the downloader module. Attackers can perform man-in-the-middle attacks or DNS poisoning to inject malicious package contents that are extracted without validation.
Severity
6.5 (Medium)
7.1 (High)
7.1 (High)
N/A (UNKNOWN)
References
| URL | Type | ||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
|
|||||||||||||||||||||||
{
"affected": [
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python-nltk",
"binary_version": "2.0~b9-0ubuntu4.1~esm6"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:14.04:LTS",
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk@2.0~b9-0ubuntu4.1~esm6?arch=source\u0026distro=esm-infra-legacy/trusty"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"2.0~b9-0ubuntu4",
"2.0~b9-0ubuntu4.1~esm2",
"2.0~b9-0ubuntu4.1~esm4",
"2.0~b9-0ubuntu4.1~esm5",
"2.0~b9-0ubuntu4.1~esm6"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python-nltk",
"binary_version": "3.1-1ubuntu0.1+esm4"
},
{
"binary_name": "python3-nltk",
"binary_version": "3.1-1ubuntu0.1+esm4"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:16.04:LTS",
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk@3.1-1ubuntu0.1+esm4?arch=source\u0026distro=esm-apps-legacy/xenial"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"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",
"3.1-1ubuntu0.1+esm4"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python-nltk",
"binary_version": "3.2.5-1ubuntu0.1+esm4"
},
{
"binary_name": "python3-nltk",
"binary_version": "3.2.5-1ubuntu0.1+esm4"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:18.04:LTS",
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk@3.2.5-1ubuntu0.1+esm4?arch=source\u0026distro=esm-apps/bionic"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"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",
"3.2.5-1ubuntu0.1+esm4"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-nltk",
"binary_version": "3.4.5-2ubuntu0.1~esm4"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:20.04:LTS",
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk@3.4.5-2ubuntu0.1~esm4?arch=source\u0026distro=esm-apps/focal"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"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",
"3.4.5-2ubuntu0.1~esm4"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-nltk",
"binary_version": "3.7-1ubuntu0.1~esm2"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:22.04:LTS",
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk@3.7-1ubuntu0.1~esm2?arch=source\u0026distro=esm-apps/jammy"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.5-1",
"3.6.5-1",
"3.6.7-1",
"3.7-1",
"3.7-1ubuntu0.1~esm1",
"3.7-1ubuntu0.1~esm2"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-nltk",
"binary_version": "3.8.1-1ubuntu0.1~esm2"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:24.04:LTS",
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk@3.8.1-1ubuntu0.1~esm2?arch=source\u0026distro=esm-apps/noble"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.8.1-1",
"3.8.1-1ubuntu0.1~esm1",
"3.8.1-1ubuntu0.1~esm2"
]
},
{
"ecosystem_specific": {
"binaries": [
{
"binary_name": "python3-nltk",
"binary_version": "3.9.2-1ubuntu0.1~esm2"
}
]
},
"package": {
"ecosystem": "Ubuntu:Pro:26.04:LTS",
"name": "nltk",
"purl": "pkg:deb/ubuntu/nltk@3.9.2-1ubuntu0.1~esm2?arch=source\u0026distro=esm-apps/resolute"
},
"ranges": [
{
"events": [
{
"introduced": "0"
}
],
"type": "ECOSYSTEM"
}
],
"versions": [
"3.9.1-2",
"3.9.1-2build1",
"3.9.2-1",
"3.9.2-1ubuntu0.1~esm1",
"3.9.2-1ubuntu0.1~esm2"
]
}
],
"aliases": [],
"details": "NLTK before 3.9.3 fails to verify file integrity after downloading packages and before extraction in the downloader module. Attackers can perform man-in-the-middle attacks or DNS poisoning to inject malicious package contents that are extracted without validation.",
"id": "UBUNTU-CVE-2026-63310",
"modified": "2026-09-02T16:20:06Z",
"published": "2026-08-22T15:16:00Z",
"references": [
{
"type": "REPORT",
"url": "https://ubuntu.com/security/CVE-2026-63310"
},
{
"type": "REPORT",
"url": "https://www.cve.org/CVERecord?id=CVE-2026-63310"
},
{
"type": "REPORT",
"url": "https://github.com/nltk/nltk/security/advisories/ghsa-5wp5-5229-5g6q"
},
{
"type": "REPORT",
"url": "https://security-tracker.debian.org/tracker/cve-2026-63310"
},
{
"type": "REPORT",
"url": "https://github.com/cveproject/cvelistv5/tree/main/cves/2026/63xxx/cve-2026-63310.json"
},
{
"type": "REPORT",
"url": "https://nvd.nist.gov/vuln/detail/cve-2026-63310"
},
{
"type": "REPORT",
"url": "https://www.vulncheck.com/advisories/nltk-before-missing-post-download-integrity-verification"
}
],
"related": [],
"schema_version": "1.7.0",
"severity": [
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
},
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:H/A:N",
"type": "CVSS_V3"
},
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N",
"type": "CVSS_V4"
},
{
"score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:L/I:H/A:H",
"type": "CVSS_V3"
},
{
"score": "medium",
"type": "Ubuntu"
}
],
"upstream": [
"CVE-2026-63310"
],
"withdrawn": "2026-09-16T11:36:44Z"
}
Loading…
Trend slope:
-
(linear fit over daily sighting counts)
Show additional events:
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Experimental. This forecast is provided for visualization only and may change without notice. Do not use it for operational decisions.
Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or observed by the user.
- Confirmed: The vulnerability has been validated from an analyst's perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
- Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
- Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
- Not confirmed: The user expressed doubt about the validity of the vulnerability.
- Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the
vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base
model, served locally by ML-Gateway.
They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.
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Related by attack behaviour
Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.
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