CVE-2026-12243

nltk: NLTK: Information disclosure via path traversal vulnerability

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Published Jun 30, 2026 CVSS 3.1 · 7.5 High EPSS n/a KEV · Not listed
Description
This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-m42h-3232-vpv3 nltk: Arbitrary File Read via Path Traversal in nltk.data.load() through Percent-Encoded Sequences
History
Type Values Removed Values Added
Title Path Traversal via Percent-Encoding in nltk.data.find() and nltk.data.load() nltk: NLTK: Information disclosure via path traversal vulnerability
CPEs cpe:2.3:a:nltk:nltk:3.9.4:*:*:*:*:*:*:*
Vendors & Products Nltk nltk
Metrics cvssV3_0

{'score': 7.5, 'vector': 'CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}

ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}
Type Values Removed Values Added
Description NLTK version 3.9.4 is vulnerable to a path traversal attack due to an incomplete fix for GitHub Issue #3504. The `_UNSAFE_NO_PROTOCOL_RE` regex in `nltk/data.py` checks for literal `../` sequences but fails to account for percent-encoded traversal sequences such as `..%2f`. The `url2pathname()` function decodes these sequences after the validation step, allowing an attacker to bypass the protection. This vulnerability enables an attacker to read arbitrary files accessible to the Python process by controlling the resource name parameter passed to `nltk.data.load()` or `nltk.data.find()`. The issue affects applications that rely on NLTK for resource loading, including NLP web applications, Jupyter notebooks, and CLI tools. The default `pathsec.ENFORCE=False` setting exacerbates the impact by not blocking the file read at the `open()` stage. This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.
Type Values Removed Values Added
References
Metrics threat_severity

None

 cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}

threat_severity

Important
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}
Type Values Removed Values Added
First Time appeared Nltk
Nltk nltk/nltk
Vendors & Products Nltk
Nltk nltk/nltk
Type Values Removed Values Added
Description NLTK version 3.9.4 is vulnerable to a path traversal attack due to an incomplete fix for GitHub Issue #3504. The `_UNSAFE_NO_PROTOCOL_RE` regex in `nltk/data.py` checks for literal `../` sequences but fails to account for percent-encoded traversal sequences such as `..%2f`. The `url2pathname()` function decodes these sequences after the validation step, allowing an attacker to bypass the protection. This vulnerability enables an attacker to read arbitrary files accessible to the Python process by controlling the resource name parameter passed to `nltk.data.load()` or `nltk.data.find()`. The issue affects applications that rely on NLTK for resource loading, including NLP web applications, Jupyter notebooks, and CLI tools. The default `pathsec.ENFORCE=False` setting exacerbates the impact by not blocking the file read at the `open()` stage.
Title Path Traversal via Percent-Encoding in nltk.data.find() and nltk.data.load()
Weaknesses CWE-22
References
Metrics cvssV3_0

{'score': 7.5, 'vector': 'CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N'}
Earlier changes (1)
Weaknesses

Sources

Status
REJECTED
Assigner
@huntr_ai
Published
Updated
Aug 18, 2026, 8:33 AM
Reserved
Jun 15, 2026, 6:24 AM

View source JSON

Updated

JSON

Status
Rejected
Published
Jun 30, 2026, 1:16 AM
Modified
Oct 16, 2026, 2:10 PM

View source JSON

Severity
Important
Public date
Jun 30, 2026, 12:14 AM

View source Bugzilla JSON

No data.