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CVE-2026-42266 high CVSS 8.8

Vulnerability in jupyterlab (CVE-2026-42266)

Summary

Vulnerability in jupyterlab (CVE-2026-42266). Successful exploitation can lead to full system takeover. Exploitable via allowed_extensions_uris. Mitigation: upgrade to 4.5.7 or later.

Original description

The description as published by the source.

JupyterLab is an extensible environment for interactive and reproducible computing, based on the Jupyter Notebook Architecture. From 4.0.0 to 4.5.6, the allow-list of extensions that can be installed from PyPI Extension Manager (allowed_extensions_uris) is not correctly enforced by JupyterLab. The PyPI Extension Manager was not contained to packages listed on the default PyPI index. This vulnerability is fixed in 4.5.7.

Source: NIST National Vulnerability Database 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-2026-42266 has been found in jupyterlab.
Attackers can target a specific entry point like allowed_extensions_uris over the network to misuse the product.
Successful exploitation can lead to full system takeover. CVSS score: 8.8/10.
What to do: upgrade jupyterlab to 4.5.7 or later.
If unsure, ask your IT team or search "jupyterlab CVE-2026-42266" on the vendor's site.

CVE-2026-42266 (jupyterlab) — CWE-88 / CVSS v3 8.8
Attack vector: remote (network-reachable) / no user interaction
Attack surface: allowed_extensions_uris / jupyterlab
Patched: 4.5.7 — 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-88) exists in jupyterlab. Attackers reach the vulnerable code path via allowed_extensions_uris.

📍 Affected scope

Check the vendor advisory for the affected versions of jupyterlab. Attack surface: allowed_extensions_uris / jupyterlab.

🔥 Severity

Severity: High (CVSS 8.8/10). Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to 4.5.7.

🛡️ 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 'jupyterlab' . 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 'jupyterlab' . | 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 jupyterlab 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 jupyterlab to 4.5.7

    ステージング環境で 4.5.7 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

Bitnami jupyterlab
[{"type":"SEMVER","events":[{"introduced":"4.0.0"},{"fixed":"4.5.7"}]}]
PyPI jupyterlab
[{"type":"ECOSYSTEM","events":[{"introduced":"4.0.0"},{"fixed":"4.5.7"}]}]
pip jupyterlab
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.5.7"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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