{"schemaVersion":3,"id":"CVE-2026-6657","aliases":["GHSA-v42x-x7jp-845h","PYSEC-2026-3472","UBUNTU-CVE-2026-6657","DEBIAN-CVE-2026-6657"],"status":"published","duplicateOf":null,"title":null,"description":"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`. 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