cvedb.io
CVE-2026-6657
HIGH · CVSS 8.8
EPSS exploitation probability: 0%
Published 2026-06-03T16:16:31.710 · Last modified 2026-06-30T19:01:13.917

Summary

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 `Origin` header, which only anchors at the start of the string. This allows attacker-controlled domains such as `trusted.example.com.evil.com` to pass validation against patterns intended to match `trusted.example.com`. The vulnerability affects multiple locations in the codebase, including CORS headers, WebSocket connections, referer validation, and login redirects, potentially enabling phishing attacks, arbitrary code execution, and unauthorized access to sensitive API responses.

Affected products

jupyter — jupyter_server

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.