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CVE-2026-12243
high
CVSS 7.5
Path Traversal in nltk (CVE-2026-12243)
Summary
path traversal in nltk (CVE-2026-12243). Confidential information can be exposed externally. Mitigation: upgrade to `3.10.0` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-12243** has been found in nltk.
Confidential information can be exposed externally. CVSS score: 7.5/10.
What to do: upgrade nltk to **3.10.0** or later.
If unsure, ask your IT team or search "nltk CVE-2026-12243" on the vendor's site.
CVE-2026-12243 (nltk) — CWE-22 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Patched: `3.10.0` — apply immediately
Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs.
Refs: see the GHSA / vendor advisory / patched release linked on this page.
❓ What is the problem
**Path traversal** (CWE-22) exists in nltk.
📍 Affected scope
nltk — .
🔥 Severity
Severity: High (CVSS 7.5/10). Confidential information can be exposed externally
🔧 How to fix
Update to **3.10.0**.
🛡️ Workaround
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'nltk' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.
Response Actions (7 steps)
Concrete steps and command examples for SOC/SRE teams to execute in order
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1Identify exposure identify
grep -r 'nltk' . | grep -v node_modulesリポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で `nltk` を grep し、稼働しているサービス・バージョンを把握する。
-
6Apply patch patch
Upgrade nltk to 3.10.0ステージング環境で 3.10.0 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 3 で見つけた異常検知の続報チェックを含めること。
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7Post-deployment verification verify
Confirm patched version is live in productionパッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 3 と同じログクエリでアラート再発が無いか継続監視。
Affected packages
pip
nltk
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.10.0"}]}]
References
- web https://huntr.com/bounties/39aa9354-54ca-4e77-96da-580eb1fe6ed1
- web https://nvd.nist.gov/vuln/detail/CVE-2026-12243
- web https://github.com/advisories/GHSA-q5h6-fcf5-49g9
- web https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-597.yaml
- web https://github.com/nltk/nltk/security/advisories/GHSA-m42h-3232-vpv3
- web https://github.com/nltk/nltk/issues/3504
- web https://github.com/nltk/nltk/pull/3522
- web https://github.com/nltk/nltk/commit/aec4fce1b84ad725b8975f7365b23a4f626572a9
- web https://securityinfinity.com/research/path-traversal-in-nltks-nltk-data-load-via-percent-encoded-sequences
- web https://github.com/advisories/GHSA-m42h-3232-vpv3