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CVE-2026-42557 critical CVSS 9.6

Cross-Site Scripting (XSS) in jupyterlab (CVE-2026-42557)

Summary

cross-site scripting in jupyterlab (CVE-2026-42557). Successful exploitation can lead to full system takeover. Exploitable via ``button``. Mitigation: upgrade to `4.5.7` or later.

AI summary snake-internal / snake-material-v2

A vulnerability tracked as **CVE-2026-42557** has been found in jupyterlab. Attackers can target a specific entry point like ``button`` over the network to misuse the product. Successful exploitation can lead to full system takeover. CVSS score: 9.6/10. What to do: upgrade jupyterlab to **4.5.7** or later. If unsure, ask your IT team or search "jupyterlab CVE-2026-42557" on the vendor's site.
CVE-2026-42557 (jupyterlab) — CWE-79 / CVSS v3 9.6 Attack vector: remote (network-reachable) / unauthenticated Attack surface: `button` / `CommandLinker` / `document.body` / `JupyterFrontEnd` 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
**Cross-site scripting (XSS)** (CWE-79) exists in jupyterlab. Attackers reach the vulnerable code path via ``button`` without authentication.
📍 Affected scope
jupyterlab — . Attack surface: `button` / `CommandLinker` / `document.body` / `JupyterFrontEnd`.
🔥 Severity
Severity: Critical (CVSS 9.6/10). 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 (7 steps)

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. 6
    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。

  3. 7
    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 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

PyPI jupyterlab
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.5.7"}]}]
PyPI notebook
[{"type":"ECOSYSTEM","events":[{"introduced":"7.0.0"},{"fixed":"7.5.6"}]}]
pip jupyterlab
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.5.7"}]}]
pip notebook
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"7.5.6"}]}]
Bitnami jupyter-base-notebook
[{"type":"SEMVER","events":[{"introduced":"7.0.0"},{"fixed":"7.5.6"}]}]
Bitnami jupyter-notebook
[{"type":"SEMVER","events":[{"introduced":"7.0.0"},{"fixed":"7.5.6"}]}]
Bitnami jupyterlab
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"4.5.7"}]}]

References

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