What is CVE-2026-6657?

CVE-2026-6657 is a high-severity vulnerability in Jupyter Jupyter/jupyter, classified under Origin Validation Error. CVSS score: 8.8/10. Published 2026-06-03.

How severe is CVE-2026-6657?

High severity. CVSS v3 base score is 8.8 out of 10.

Vulnerability in Jupyter Jupyter/jupyter

CVE-2026-6657

A vulnerability in jupyter-server versions 1.12.0 through 2.17.0 allows an attacker to bypass CORS origin validation when the `allow_origin_pat` configuration is used. The issue arises from the use of `re.match()` for validating the `Origi…

EPSS: 0.002 (9.6th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 8.8 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H.

Affected products

Jupyter Jupyter/jupyter — versions unspecified
Jupyter Jupyter_server

Weakness classification (CWE)

CWE-346 — Origin Validation Error

References

security@huntr.dev (Exploit, Third Party Advisory)

Frequently asked questions

What is CVE-2026-6657?: CVE-2026-6657 is a high-severity vulnerability in Jupyter Jupyter/jupyter, classified under Origin Validation Error. CVSS score: 8.8/10. Published 2026-06-03.
How severe is CVE-2026-6657?: High severity. CVSS v3 base score is 8.8 out of 10.