CVE WatchJul 24, 2026

CVE-2026-40110

Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the Origin header validation uses Python's re.ma

CVSS

7.3

High

EPSS

0.3%

p27

KEV

—

Exploit Today

0-100

Published: May 5, 2026 · Last modified: Jul 24, 2026 · CWE-777 · CWE-625

EPSS · 30d

0.3%EPSS · 30 days0.3%

2026-08-182026-09-14

Technical description

Jupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the Origin header validation uses Python's re.match() to check incoming origins against the allow_origin_pat configuration value. Because re.match() only anchors at the start of the string and does not require a full match, a pattern intended to match only a trusted domain (e.g., trusted.example.com) will also match any origin that begins with that domain followed by additional characters (e.g., trusted.example.com.evil.com). An attacker who controls such a domain can bypass the CORS origin restriction and make cross-origin requests to the Jupyter Server API from an untrusted site. This issue has been fixed in version 2.18.0.

Official references

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