How severe is CVE-2019-10255?

CVE-2019-10255 has a CVSS score of 6.1/10, rated MEDIUM. Review your exposure and patch according to your risk tolerance.

Which packages are affected by CVE-2019-10255?

CVE-2019-10255 affects the following packages: notebook (PyPI), jupyterhub (PyPI). Ecosystems affected: PyPI.

How do I fix CVE-2019-10255?

Update notebook to 5.7.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-10255 is resolved across your whole dependency graph.

How do I detect CVE-2019-10255 in my PyPI dependencies?

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.

How do I mitigate CVE-2019-10255 if there is no patch (or I can't update yet)?

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.

Is CVE-2019-10255 actively exploited in the wild?

No public exploit code has been indexed for CVE-2019-10255 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What is the EPSS score for CVE-2019-10255?

CVE-2019-10255 has an EPSS (Exploit Prediction Scoring System) score of 1.8%, placing it in the 78th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2019-10255?

CVE-2019-10255 is classified as Open Redirect (CWE-601). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2019-10255 published, and has it been updated?

CVE-2019-10255 was published on March 28, 2019 and was last updated on October 24, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

🐍

🐍 PyPI

Not in CISA KEV

MEDIUM severity

CVE-2019-10255 — notebook

MEDIUMFix: jupyter/notebook@08c4c89

CVE-2019-10255 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 vulnerability in jupyterhub and notebook

Also known asGHSA-rv62-4pmj-xw6hPYSEC-2026-2683PYSEC-2026-647

Published

Mar 28, 2019

Updated

Oct 24, 2026

Affected

2 pkgs

Patched

2 / 2

Exploits

None indexed

Exploitation data as of Nov 5, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.8%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs78th percentile — riskier than 78% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

2 pkgs affected

🐍notebook🐍jupyterhub

Real-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

An Open Redirect vulnerability for all browsers in Jupyter Notebook before 5.7.7 and some browsers (Chrome, Firefox) in JupyterHub before 0.9.5 allows crafted links to the login page, which will redirect to a malicious site after successful login. Servers running on a base_url prefix are not affected.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
🐍PyPI	`notebook`	all versions	5.7.8`pip install --upgrade 'notebook==5.7.8'`
🐍PyPI	`jupyterhub`	all versions	0.9.6`pip install --upgrade 'jupyterhub==0.9.6'`

Affected Products

2 products · 2 configurations

Application

jupyterhubjupyter

< 0.9.5

range

Application

notebookjupyter

< 5.7.7

range

Detection & mitigation playbook

Open-source dependency

Detect
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 5.7.8 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2019-10255 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.

Frequently Asked Questions

O3 Security · Impact-Aware SCA

Is CVE-2019-10255 in your dependencies?

Find it across PyPI, including transitive dependencies.

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