Cross-Site Request Forgery (CSRF) in jupyterhub (CVE-2026-40864)
Summary
Vulnerability in jupyterhub (CVE-2026-40864). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 5.4.5 or later.
Original description
The description as published by the source.
JupyterHub is software that allows users to create a multi-user server for Jupyter notebooks. In versions 4.1.0 through 5.4.4, XSRF protection (updated in 4.1.0) inappropriately treated requests with Sec-Fetch-Mode: no-cors as same-origin requests, bypassing XSRF checks. The JSON API is not affected, only HTTP form endpoints, such as /hub/spawn and /hub/accept-share, meaning attackers could trigger server spawn (but not access the server) and if the attacker is a JupyterHub user permitted to share access to their server, cause a user to accept a share and have access to the attacker's server. This issue has been fixed in version 5.4.5. If developers are unable to immediately upgrade, they can temporarily mitigate this issue by dropping requests to JupyterHub with Sec-Fetch-Mode: no-cors if they are using a reverse proxy.
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-2026-40864 has been found in jupyterhub.
Risk of unauthorized operations or information disclosure. CVSS score: 5.4/10.
What to do: upgrade jupyterhub to 5.4.5 or later.
If unsure, ask your IT team or search "jupyterhub CVE-2026-40864" on the vendor's site.
CVE-2026-40864 (jupyterhub) — CWE-352 / CVSS v3 5.4
Attack vector: remote (network-reachable) / unauthenticated
Patched: 5.4.5 — 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.
CSRF (CWE-352) exists in jupyterhub.
Check the vendor advisory for the affected versions of jupyterhub.
Severity: Medium (CVSS 5.4/10). Risk of unauthorized operations or information disclosure.
Update to 5.4.5.
Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'jupyterhub' . 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
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1Identify exposure identify
grep -r 'jupyterhub' . | 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
jupyterhubを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply patch patch
Upgrade jupyterhub to 5.4.5ステージング環境で 5.4.5 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。
-
3Post-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
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Debian DEBIAN-CVE-2026-40864 jupyterhub
- Ubuntu UBUNTU-CVE-2026-40864 jupyterhub
References
- advisory github.com
- advisory nvd.nist.gov
- advisory github.com
- package github.com
- patch github.com
- web github.com