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CVE-2026-62385 medium CVSS 5.9

Vulnerability in nltk (CVE-2026-62385)

Summary

Vulnerability in nltk (CVE-2026-62385). Confidential information can be exposed externally. Exploitable via FramenetCorpusReader.frame_by_name. Mitigation: upgrade to 3.10.0 or later.

Original description

The description as published by the source.

Summary

Published nltk==3.9.4 still contains several XML-reader entrypoints that build parser paths from caller-controlled selectors or trusted-looking index state without preserving the corpus-root boundary.

Details

  • Vulnerability type: Path traversal and trusted-root bypass
  • Affected component: FramenetCorpusReader.frame_by_name, FramenetCorpusReader.doc, FramenetCorpusReader.lu, NKJPCorpusReader.header
  • Affected versions: Published 3.9.4 reproduced. Current source v3.10.0-rc2 acted as a negative control and blocked the same payloads.
  • Patched versions: Patched in version 3.10.0, which includes the path-safety rejections seen in the release candidate.
  • Root cause: Stable reader paths still construct raw XML filenames from unsafe selectors, poisoned index state, or unsafe file identifiers.

I confirmed four public stable entrypoints return parsed outside-root content: a parent-segment traversal frame name, a poisoned fulltext index filename, a poisoned LU id, and an unsafe NKJP header file identifier. Current source rejects the same payloads with explicit path-safety errors, which shows the bug is real but version-scoped to the published stable package.

PoC

Preconditions

  • The application exposes FrameNet or NKJP reader APIs while trusting NLTK to keep XML parsing inside a corpus root.

Steps

  1. Create a minimal FrameNet or NKJP corpus root and place attacker-chosen XML files outside that root.
  2. Feed unsafe se…

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-2026-62385 has been found in nltk.
Attackers can target a specific entry point like FramenetCorpusReader.frame_by_name over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 5.9/10.
What to do: upgrade nltk to 3.10.0 or later.
If unsure, ask your IT team or search "nltk CVE-2026-62385" on the vendor's site.

CVE-2026-62385 (nltk) — CWE-73 / CVSS v3 5.9
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: FramenetCorpusReader.frame_by_name / FramenetCorpusReader.doc / FramenetCorpusReader.lu / NKJPCorpusReader.header
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

A vulnerability (CWE-73) exists in nltk. Attackers reach the vulnerable code path via FramenetCorpusReader.frame_by_name without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of nltk. Attack surface: FramenetCorpusReader.frame_by_name / FramenetCorpusReader.doc / FramenetCorpusReader.lu / NKJPCorpusReader.header.

🔥 Severity

Severity: Medium (CVSS 5.9/10). 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

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 3.10.0

    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":"3.10.0"}]}]
PyPI nltk
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.10.0"}]}]

References

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