{"dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": {"cveId": "CVE-2026-6657", "assignerOrgId": "c09c270a-b464-47c1-9133-acb35b22c19a", "state": "PUBLISHED", "assignerShortName": "@huntr_ai", "dateReserved": "2026-04-20T08:13:54.544Z", "datePublished": "2026-06-03T15:06:56.598Z", "dateUpdated": "2026-06-03T17:25:20.310Z"}, "containers": {"cna": {"title": "CORS Origin Validation Bypass in jupyter-server", "providerMetadata": {"orgId": "c09c270a-b464-47c1-9133-acb35b22c19a", "shortName": "@huntr_ai", "dateUpdated": "2026-06-03T15:06:56.598Z"}, "descriptions": [{"lang": "en", "value": "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": [{"vendor": "jupyter", "product": "jupyter/jupyter", "versions": [{"version": "unspecified", "status": "affected", "versionType": "custom", "lessThanOrEqual": "latest"}]}], "references": [{"url": "https://huntr.com/bounties/18f642db-3569-43b3-b58d-ff97be4b09d7"}], "metrics": [{"cvssV3_0": {"version": "3.0", "attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "baseScore": 6.1, "baseSeverity": "MEDIUM"}}], "problemTypes": [{"descriptions": [{"type": "CWE", "lang": "en", "description": "CWE-346 Origin Validation Error", "cweId": "CWE-346"}]}], "source": {"advisory": "18f642db-3569-43b3-b58d-ff97be4b09d7", "discovery": "EXTERNAL"}}, "adp": [{"references": [{"url": "https://huntr.com/bounties/18f642db-3569-43b3-b58d-ff97be4b09d7", "tags": ["exploit"]}], "metrics": [{"other": {"type": "ssvc", "content": {"timestamp": "2026-06-03T17:24:16.863193Z", "id": "CVE-2026-6657", "options": [{"Exploitation": "poc"}, {"Automatable": "no"}, {"Technical Impact": "partial"}], "role": "CISA Coordinator", "version": "2.0.3"}}}], "title": "CISA ADP Vulnrichment", "providerMetadata": {"orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-03T17:25:20.310Z"}}]}}

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{"cveTags": [], "descriptions": [{"lang": "en", "value": "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."}], "id": "CVE-2026-6657", "lastModified": "2026-06-04T15:25:53.963", "metrics": {"cvssMetricV30": [{"cvssData": {"attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "NONE", "baseScore": 6.1, "baseSeverity": "MEDIUM", "confidentialityImpact": "LOW", "integrityImpact": "LOW", "privilegesRequired": "NONE", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.0/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "version": "3.0"}, "exploitabilityScore": 2.8, "impactScore": 2.7, "source": "security@huntr.dev", "type": "Secondary"}]}, "published": "2026-06-03T16:16:31.710", "references": [{"source": "security@huntr.dev", "url": "https://huntr.com/bounties/18f642db-3569-43b3-b58d-ff97be4b09d7"}, {"source": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "url": "https://huntr.com/bounties/18f642db-3569-43b3-b58d-ff97be4b09d7"}], "sourceIdentifier": "security@huntr.dev", "vulnStatus": "Awaiting Analysis", "weaknesses": [{"description": [{"lang": "en", "value": "CWE-346"}], "source": "security@huntr.dev", "type": "Secondary"}]}

{"bugzilla": {"description": "jupyter-server: jupyter-server: Arbitrary code execution due to CORS origin validation bypass", "id": "2484420", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2484420"}, "csaw": false, "cvss3": {"cvss3_base_score": "6.1", "cvss3_scoring_vector": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N", "status": "draft"}, "cwe": "CWE-625", "details": ["A flaw was found in jupyter-server. A remote attacker can bypass Cross-Origin Resource Sharing (CORS) origin validation when the `allow_origin_pat` configuration is used. This vulnerability allows malicious domains to pass validation against patterns intended for trusted domains. This could lead to arbitrary code execution, unauthorized access to sensitive API responses, and phishing attacks."], "mitigation": {"lang": "en:us", "value": "Restrict network access to the jupyter-server to only trusted clients and networks. This can be achieved by configuring firewall rules to limit inbound connections to the ports used by jupyter-server, thereby reducing the attack surface for this CORS bypass vulnerability. A restart or service reload may be required for firewall changes to take effect."}, "name": "CVE-2026-6657", "package_state": [{"cpe": "cpe:/a:redhat:migration_toolkit_applications:8", "fix_state": "Fix deferred", "package_name": "mta/mta-solution-server-rhel9", "product_name": "Migration Toolkit for Applications 8"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-th06-cpu-torch210-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-th06-cpu-torch291-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-th06-cuda130-torch210-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-th06-cuda130-torch291-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-th06-rocm64-torch291-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-workbench-jupyter-datascience-cpu-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-workbench-jupyter-minimal-cpu-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-workbench-jupyter-minimal-cuda-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-workbench-jupyter-minimal-rocm-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-workbench-jupyter-pytorch-cuda-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-workbench-jupyter-pytorch-llmcompressor-cuda-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-workbench-jupyter-pytorch-rocm-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-workbench-jupyter-tensorflow-cuda-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-workbench-jupyter-tensorflow-rocm-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}, {"cpe": "cpe:/a:redhat:openshift_ai", "fix_state": "Fix deferred", "package_name": "rhoai/odh-workbench-jupyter-trustyai-cpu-py312-rhel9", "product_name": "Red Hat OpenShift AI (RHOAI)"}], "public_date": "2026-06-03T15:06:56Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-6657\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-6657\nhttps://huntr.com/bounties/18f642db-3569-43b3-b58d-ff97be4b09d7"], "statement": "The impact for this flaw is set to Moderate because exploitation requires\n(1) allow_origin_pat to be configured \u2014 a non-default CORS regex allowlist; when allow_origin\nis set it takes precedence \n(2) user interaction: the victim must visit an attacker-controlled origin while authenticated to Jupyter. In that case, broken re.match() validation can allow cross-origin Jupyter API access (CWE-346). This is not unauthenticated RCE on default supported configurations.", "threat_severity": "Moderate"}