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CVE-2026-62384 high CVSS 7.5

Path Traversal in nltk (CVE-2026-62384)

Summary

Path traversal in nltk (CVE-2026-62384). Confidential information can be exposed externally. Exploitable via required_root. Mitigation: upgrade to 3.10.2 or later.

Original description

The description as published by the source.

This is a new, distinct vulnerability: a bypass of the fix already published as GHSA-xh95-f55m-82fw ("Path traversal in NLTK FramenetCorpusReader.frame() allows arbitrary XML file read, bypassing the nltk.pathsec sandbox"), not a duplicate of it.

Summary

The original advisory was fixed (PR #3581) by adding _reject_unsafe_path_component(), which blocks literal /, \, .., and Windows drive prefixes in caller-/corpus-supplied names. It never resolves symlinks. All three call sites that use this guard still resolve the resulting path through self.abspath() (nltk/corpus/reader/api.py, self._root.join(fileid)), which is a plain lexical join, not the symlink-resolving, required_root-scoped check that CorpusReader.open() (and NKJPCorpusReader's own fix for its sibling advisory) correctly use elsewhere in this same codebase.

A symlink placed inside the corpus's own subdirectory, with a name containing no separators at all, passes the guard cleanly and reads a file completely outside the corpus root.

Affected code (nltk/corpus/reader/framenet.py)

  • frame_by_name() reads /.xml
  • _lu_file() reads /lu.xml
  • doc() reads /

All three follow the same chain: _reject_unsafe_path_component(value, ...), then self.abspath(os.path.join(subdir, value)), then XMLCorpusView(...), opened via PathPointer.open() with no required_root.…

Source: GitHub Security Advisories (Global) NVD GitHub Advisory

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as CVE-2026-62384 has been found in nltk.
Attackers can target a specific entry point like required_root over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 7.5/10.
What to do: upgrade nltk to 3.10.2 or later.
If unsure, ask your IT team or search "nltk CVE-2026-62384" on the vendor's site.

CVE-2026-62384 (nltk) — CWE-22 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: required_root / NKJPCorpusReader / main / secret_path
Patched: 3.10.2 — 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. Attackers reach the vulnerable code path via required_root without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of nltk. Attack surface: required_root / NKJPCorpusReader / main / secret_path.

🔥 Severity

Severity: High (CVSS 7.5/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 3.10.2.

🛡️ 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

Concrete steps and command examples for SOC/SRE teams to execute in order

  1. 1
    Identify 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。

  2. 2
    Apply patch patch 
    Upgrade nltk to 3.10.2

    ステージング環境で 3.10.2 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を含めること。

  3. 3
    Post-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。本番ではアクセスログ・WAF 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":"3.10.2"}]}]
PyPI nltk
[{"type":"ECOSYSTEM","events":[{"introduced":"3.10.0"},{"fixed":"3.10.2"}]}]

References

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