CVE-2020-26215 is a medium-severity (CVSS 6.1) Open Redirect vulnerability in notebook. A fix is available for notebook — see the affected versions and patch details below.
Open redirect in Jupyter Notebook
EPSS Exploitation Probability
Probability of exploitation in the next 30 days, from FIRST.org EPSS.
How urgent is this, really
CVE-2020-26215 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.
Where this sits among everything scored
Of 385,987 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.
Real-World Exposure
notebookReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.
Description
Impact
What kind of vulnerability is it? Who is impacted?
Open redirect vulnerability - a maliciously crafted link to a notebook server could redirect the browser to a different website.
All notebook servers are technically affected, however, these maliciously crafted links can only be reasonably made for known notebook server hosts. A link to your notebook server may appear safe, but ultimately redirect to a spoofed server on the public internet.
Patches
Has the problem been patched? What versions should users upgrade to?
Patched in notebook 6.1.5
References
For more information
If you have any questions or comments about this advisory, or vulnerabilities to report, please email our security list [email protected].
Credit: zhuonan li of Alibaba Application Security Team
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 🐍PyPI | notebook | all versions | 6.1.5pip install --upgrade 'notebook==6.1.5' |
Affected Products
debian linuxdebiannotebookjupyterDetection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for notebook, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update notebook to 6.1.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2020-26215 is resolved across your whole dependency graph.
Workarounds
Stop reflecting attacker-controlled destinations: resolve every redirect target against an allowlist of paths or hosts you own, prefer a server-side key over a full URL in the request, and reject absolute URLs entirely where the flow only ever needs a relative one.
Fixing This On Your OS
If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.
Frequently Asked Questions
Is CVE-2020-26215 in your dependencies?
Find it across PyPI, including transitive dependencies.