{"cve":"CVE-2026-40110","nvd":{"published":"2026-05-05T22:16:00.663","modified":"2026-07-24T21:10:00.143","status":"Modified","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.","cvss_v4":{"vector":"CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:L/SC:L/SI:L/SA:L","score":7.6},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N","score":7.3},"cwes":["CWE-777","CWE-625"],"references":["https://github.com/jupyter-server/jupyter_server/commit/057869a327c46730afede3eab0ca2d2e3e74acea","https://github.com/jupyter-server/jupyter_server/commit/49b34392feaa97735b3b777e3baf8f22f2a14ed8","https://github.com/jupyter-server/jupyter_server/pull/603","https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-24qx-w28j-9m6p","https://access.redhat.com/errata/RHSA-2026:43038"],"products":["jupyter:jupyter_server"],"source":"nvd","synced_at":"2026-10-19T22:33:55.586217763+00:00"},"epss":{"cve":"CVE-2026-40110","score":0.00313,"percentile":0.24238,"date":"2026-11-01"},"kev":null,"osv":[{"id":"GHSA-24qx-w28j-9m6p","url":"https://osv.dev/vulnerability/GHSA-24qx-w28j-9m6p","summary":"Jupyter Server has a  CORS Origin Validation Bypass via `re.match()` in `allow_origin_pat`","modified":"2026-09-10T03:50:45.011553229Z","packages":[{"ecosystem":"PyPI","name":"jupyter-server","purl":"pkg:pypi/jupyter-server","ranges":["<2.18.0"],"fixed":["2.18.0"]}]},{"id":"PYSEC-2026-2187","url":"https://osv.dev/vulnerability/PYSEC-2026-2187","summary":"","modified":"2026-07-13T07:15:34.116347312Z","packages":[{"ecosystem":"PyPI","name":"jupyter-server","purl":"pkg:pypi/jupyter-server","ranges":["<2.18.0"],"fixed":["2.18.0"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}