VULNERABILITY INTELLIGENCE

CVE-2026-40110

CVSS score7.3 HIGH
EPSS probability0.31%
CISA KEVNot currently listed
Published2026-05-05
Last modified2026-07-24
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N

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.

Weakness classification

  • security-advisories@github.com: CWE-777
  • 0b0ca135-0b70-47e7-9f44-1890c2a1c46c: CWE-625

Primary references