{"vulnerability": "cve-2026-12243", "sightings": [{"uuid": "5880128e-820c-44a7-8779-3282c36b3910", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-12243", "type": "published-proof-of-concept", "source": "https://t.me/GithubRedTeam/100264", "content": "\ud83d\udea8 GitHub \u76d1\u63a7\u6d88\u606f\u63d0\u9192\n\n\ud83d\udea8 \u53d1\u73b0\u5173\u952e\u8bcd\uff1a #CVE-2026 #POC\n\n\ud83d\udce6 \u9879\u76ee\u540d\u79f0\uff1a CVE-2026-12243-NLTK-PoC\n\ud83d\udc64 \u9879\u76ee\u4f5c\u8005\uff1a morzelowski\n\ud83d\udee0 \u5f00\u53d1\u8bed\u8a00\uff1a Python\n\u2b50 Star\u6570\u91cf\uff1a 0  |  \ud83c\udf74 Fork\u6570\u91cf\uff1a 0\n\ud83d\udcc5 \u66f4\u65b0\u65f6\u95f4\uff1a 2026-08-29 16:38:16\n\n\ud83d\udcdd \u9879\u76ee\u63cf\u8ff0\uff1a\n\u65e0\u63cf\u8ff0\n\n\ud83d\udd17 \u70b9\u51fb\u8bbf\u95ee\u9879\u76ee\u5730\u5740", "creation_timestamp": "2026-08-29T20:00:26.417971Z"}, {"uuid": "ca89dfd7-cf0b-4b55-b32e-b5ef841206ad", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-12243", "type": "published-proof-of-concept", "source": "https://t.me/GithubRedTeam/100264", "content": "\ud83d\udea8 GitHub \u76d1\u63a7\u6d88\u606f\u63d0\u9192\n\n\ud83d\udea8 \u53d1\u73b0\u5173\u952e\u8bcd\uff1a #CVE-2026 #POC\n\n\ud83d\udce6 \u9879\u76ee\u540d\u79f0\uff1a CVE-2026-12243-NLTK-PoC\n\ud83d\udc64 \u9879\u76ee\u4f5c\u8005\uff1a morzelowski\n\ud83d\udee0 \u5f00\u53d1\u8bed\u8a00\uff1a Python\n\u2b50 Star\u6570\u91cf\uff1a 0  |  \ud83c\udf74 Fork\u6570\u91cf\uff1a 0\n\ud83d\udcc5 \u66f4\u65b0\u65f6\u95f4\uff1a 2026-08-29 16:38:16\n\n\ud83d\udcdd \u9879\u76ee\u63cf\u8ff0\uff1a\n\u65e0\u63cf\u8ff0\n\n\ud83d\udd17 \u70b9\u51fb\u8bbf\u95ee\u9879\u76ee\u5730\u5740", "creation_timestamp": "2026-08-30T00:00:52.954171Z"}, {"uuid": "5a420e20-74e2-48da-8b91-abd973d34b56", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-12243", "type": "seen", "source": "Telegram/ZCILXLquzGbXFQcaZlOXv9dkF48Tloh98M2Ojf7eGNskguU", "content": "", "creation_timestamp": "2026-08-29T23:00:04.773608Z"}, {"uuid": "792baa51-60fe-44f6-9a80-7ff6dd9b6d0c", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-12243", "type": "published-proof-of-concept", "source": "Telegram/ZCILXLquzGbXFQcaZlOXv9dkF48Tloh98M2Ojf7eGNskguU", "content": "", "creation_timestamp": "2026-08-30T00:00:09.390833Z"}, {"uuid": "5a5b1483-d6f7-4538-959a-b9759fe03f79", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "cve-2026-12243", "type": "seen", "source": "https://bsky.app/profile/offseq.bsky.social/post/3mphu4lougb2t", "content": "NLTK 3.9.4 has a HIGH severity path traversal flaw \u2014 percent-encoded payloads can read files via nltk.data.load(). Affects web/NLP apps & Jupyter. Review usage and restrict resource input. https://radar.offseq.com/threat/cve-2026-12243-cwe-22-improper-limitation-of-a-pat-3eae11979fc43a41 #OffSeq ...", "creation_timestamp": "2026-06-30T01:30:29.868277Z"}, {"uuid": "fc3c78df-4b5b-484b-a24f-2de8047efe60", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "cve-2026-12243", "type": "seen", "source": "https://infosec.exchange/users/offseq/statuses/116836468435158836", "content": "CVE-2026-12243: NLTK 3.9.4 suffers from a HIGH severity path traversal bug \u2014 percent-encoded sequences like ..%2f bypass directory checks, allowing arbitrary file reads in NLP apps/Jupyter/CLI. Audit usages & restrict resource loading. https://radar.offseq.com/threat/cve-2026-12243-cwe-22-improper-limitation-of-a-pat-3eae11979fc43a41 #OffSeq #NLTK #Python", "creation_timestamp": "2026-06-30T01:30:32.997816Z"}, {"uuid": "4ae01c5a-afb9-41ec-b14c-43b5ad5a238b", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-12243", "type": "seen", "source": "https://bsky.app/profile/kriptabiz.bsky.social/post/3mphut4okqz22", "content": "\u0423\u044f\u0437\u0432\u0438\u043c\u043e\u0441\u0442\u044c CVE-2026-12243 \u0432 NLTK 3.9.4: \u0443\u0433\u0440\u043e\u0437\u0430 path traversal \u0438 \u0441\u043f\u043e\u0441\u043e\u0431\u044b \u0437\u0430\u0449\u0438\u0442\u044b\n\n\n\nhttps://kripta.biz/posts/D8109989-D984-4F37-B7BF-7B36809D1F96", "creation_timestamp": "2026-06-30T01:43:05.220815Z"}, {"uuid": "a43e4b8a-d024-440d-a94b-eacc92291b3e", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-12243", "type": "seen", "source": "https://bsky.app/profile/cve.skyfleet.blue/post/3mphvan63hs2t", "content": "CVE-2026-12243 - Path Traversal via Percent-Encoding in nltk.data.find() and nltk.data.load()\nCVE ID : CVE-2026-12243\n \n Published : June 30, 2026, 12:14 a.m. | 1\u00a0hour, 31\u00a0minutes ago\n \n Description : NLTK version 3.9.4 is vulnerable to a path traversal attack due to an incomp...", "creation_timestamp": "2026-06-30T01:50:38.568333Z"}, {"uuid": "ba8c70de-d83d-4d0d-b443-3e6d108741ab", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "9f56dd64-161d-43a6-b9c3-555944290a09", "vulnerability": "CVE-2026-12243", "type": "seen", "source": "https://gist.github.com/alon710/3eb28c932c38464a242f2a0a9b534f73", "content": "# CVE-2026-12243: CVE-2026-12243: Incomplete Path Traversal Validation and Percent-Encoding Bypass in NLTK\n\n> **CVSS Score:** 7.5\n> **Published:** 2026-08-13\n> **Full Report:** https://cvereports.com/reports/CVE-2026-12243\n\n## Summary\nCVE-2026-12243 is a path traversal vulnerability in the Natural Language Toolkit (NLTK) version 3.9.4. The flaw exists because the input validation routine fails to account for percent-encoded directory traversal sequences like '..%2f' before passing them to urllib.request.url2pathname(), which decodes them into active traversal sequences.\n\n## TL;DR\nA path traversal vulnerability in NLTK 3.9.4 allows remote unauthenticated attackers to read arbitrary files via percent-encoded path traversal sequences because lexical validation occurs before URL decoding.\n\n## Exploit Status: POC\n\n## Technical Details\n\n- **CWE ID**: CWE-22\n- **Attack Vector**: Network (AV:N)\n- **CVSS Base Score**: 7.5\n- **EPSS Score**: 0.00583 (Percentile: 44.89%)\n- **Impact**: Arbitrary File Read / Information Disclosure\n- **Exploit Status**: Proof-of-Concept (PoC) documented\n- **KEV Status**: Not listed\n\n## Affected Systems\n\n- Applications employing NLTK for dynamic resource/corpora loading\n- Web-based natural language processing pipelines using NLTK 3.9.4\n- Jupyter notebooks and machine learning environments loading external corpus names\n- **NLTK (Natural Language Toolkit)**: 3.9.4 (Fixed in: `3.9.5`)\n\n## Mitigation\n\n- Upgrade NLTK to version 3.9.5 or higher.\n- Explicitly configure the path security enforcement setting in NLTK to raise errors rather than warning only: `nltk.pathsec.ENFORCE = True`.\n- Strictly sanitize user-provided file inputs and use alternative lookups like dictionary mapping instead of directly resolving paths from user strings.\n\n**Remediation Steps:**\n1. Step 1: Install NLTK version 3.9.5 via pip: `pip install -U nltk`\n2. Step 2: Add `import nltk.pathsec` and `nltk.pathsec.ENFORCE = True` at the application entry point to ensure enforcement.\n3. Step 3: If accessing files in the current directory is required, explicitly add the current directory to the search paths using `nltk.data.path.append('.')` to allow path validation rules to approve it.\n\n## References\n\n- [Official CVE Record](https://www.cve.org/CVERecord?id=CVE-2026-12243)\n- [NVD Advisory Entry](https://nvd.nist.gov/vuln/detail/CVE-2026-12243)\n- [NLTK Repository Security Commit](https://github.com/nltk/nltk/commit/aec4fce1b84ad725b8975f7365b23a4f626572a9)\n- [NLTK Security Patch Pull Request](https://github.com/nltk/nltk/pull/3522)\n- [Huntr Bug Bounty Database Entry](https://huntr.com/bounties/39aa9354-54ca-4e77-96da-580eb1fe6ed1)\n- [Wiz Vulnerability Analysis Portal](https://www.wiz.io/vulnerability-database/cve/cve-2026-12243)\n\n\n---\n*Generated by [CVEReports](https://cvereports.com/reports/CVE-2026-12243) - Automated Vulnerability Intelligence*", "creation_timestamp": "2026-08-13T22:33:03.303666Z"}, {"uuid": "57e107e3-33e0-4b00-b7bc-9af7a471260f", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "86ecb4e1-bb32-44d5-9f39-8a4673af8385", "vulnerability": "CVE-2026-12243", "type": "published-proof-of-concept", "source": "https://github.com/advisories/GHSA-m42h-3232-vpv3", "content": "", "creation_timestamp": "2026-08-13T22:35:05.885067Z"}]}