What is CVE-2019-10856?

CVE-2019-10856 is a medium-severity vulnerability in Jupyter Notebook, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.1/10. Published 2019-04-04.

How severe is CVE-2019-10856?

Medium severity. CVSS v3 base score is 6.1 out of 10.

Is CVE-2019-10856 known to be exploited?

2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.

Open Redirect in Jupyter Notebook

CVE-2019-10856

In Jupyter Notebook before 5.7.8, an open redirect can occur via an empty netloc. This issue exists because of an incomplete fix for CVE-2019-10255.

Vulnerability class: Open Redirect

Published 2019-04-04 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.

EPSS exploit prediction

EPSS: 0.013 (69.2th percentile), scored 2026-10-19.

Low probability of exploitation in the next 30 days, but still tracked. 69th percentile — 69.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.013 · newest: 0.013 · change: 0.000

Affected products

Jupyter Notebook

Weakness classification (CWE)

CWE-601 — URL Redirection to Untrusted Site (Open Redirect)

Public proof-of-concept exploits

References

blog.jupyter.org/open-redirect-vulnerability-in-jupyter-jupyterhub-adf43583f1e4 (Exploit, Vendor Advisory)
github.com/jupyter/notebook/compare/16cf97c...b8e30ea (Patch, Vendor Advisory)

Frequently asked questions

What is CVE-2019-10856?: CVE-2019-10856 is a medium-severity vulnerability in Jupyter Notebook, classified under URL Redirection to Untrusted Site (Open Redirect). CVSS score: 6.1/10. Published 2019-04-04.
How severe is CVE-2019-10856?: Medium severity. CVSS v3 base score is 6.1 out of 10.
Is CVE-2019-10856 known to be exploited?: 2 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.