Withdrawn: this CVE is not a vulnerability
The assigning CNA withdrew CVE-2026-12243 on 18 August 2026, and it carries the Rejected state at CVE.org and NVD. It must not be treated as a live finding. Its pre-withdrawal severity, score and exploitability are withheld below; the record itself is kept because withdrawals are reversible and because the reject reason is the correction worth publishing.
CVE-2026-12243
Path Traversal via Percent-Encoding in nltk.data.find() and nltk.data.load()
Description
Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority.
INFO
Published Date :
June 30, 2026, 1:16 a.m.
Last Modified :
Aug. 18, 2026, 9:16 a.m.
Remotely Exploit :
—
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.0 | HIGH | [email protected] |
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Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
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CVE Rejected by [email protected]
Aug. 18, 2026
Action Type Old Value New Value -
CVE Modified by [email protected]
Aug. 18, 2026
Action Type Old Value New Value Changed 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. Rejected reason: This CVE ID has been rejected or withdrawn by its CVE Numbering Authority. Removed CVSS V3 huntr.dev: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Removed CWE huntr.dev: CWE-22 Removed CPE Configuration OR *cpe:2.3:a:nltk:nltk:3.9.4:*:*:*:*:*:*:* Removed Reference huntr.dev: https://huntr.com/bounties/39aa9354-54ca-4e77-96da-580eb1fe6ed1 Removed Reference CISA-ADP: https://huntr.com/bounties/39aa9354-54ca-4e77-96da-580eb1fe6ed1 Removed Reference Type huntr.dev: https://huntr.com/bounties/39aa9354-54ca-4e77-96da-580eb1fe6ed1 Types: Exploit, Mitigation, Third Party Advisory Removed Reference Type CISA-ADP: https://huntr.com/bounties/39aa9354-54ca-4e77-96da-580eb1fe6ed1 Types: Exploit, Mitigation, Third Party Advisory Removed Affected [{'vendor': 'nltk', 'product': 'nltk/nltk', 'versions': [{'status': 'affected', 'version': 'unspecified', 'versionType': 'custom', 'lessThanOrEqual': 'latest'}]}] Removed SSVC {'id': 'CVE-2026-12243', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-30T13:14:09.515988Z'} -
Initial Analysis by [email protected]
Jun. 30, 2026
Action Type Old Value New Value Added CPE Configuration OR *cpe:2.3:a:nltk:nltk:3.9.4:*:*:*:*:*:*:* Added Reference Type huntr.dev: https://huntr.com/bounties/39aa9354-54ca-4e77-96da-580eb1fe6ed1 Types: Exploit, Mitigation, Third Party Advisory Added Reference Type CISA-ADP: https://huntr.com/bounties/39aa9354-54ca-4e77-96da-580eb1fe6ed1 Types: Exploit, Mitigation, Third Party Advisory -
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 30, 2026
Action Type Old Value New Value Added Reference https://huntr.com/bounties/39aa9354-54ca-4e77-96da-580eb1fe6ed1 Added SSVC {'id': 'CVE-2026-12243', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'poc'}, {'automatable': 'yes'}, {'technicalImpact': 'partial'}], 'version': '2.0.3', 'timestamp': '2026-06-30T13:14:09.515988Z'} -
New CVE Received by [email protected]
Jun. 30, 2026
Action Type Old Value New Value Added Affected [{'vendor': 'nltk', 'product': 'nltk/nltk', 'versions': [{'status': 'affected', 'version': 'unspecified', 'versionType': 'custom', 'lessThanOrEqual': 'latest'}]}] 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. Added CVSS V3 AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N Added CWE CWE-22 Added Reference https://huntr.com/bounties/39aa9354-54ca-4e77-96da-580eb1fe6ed1