{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-44727", "assignerOrgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "state": "PUBLISHED", "assignerShortName": "GitHub_M", "dateReserved": "2026-05-07T18:04:17.309Z", "datePublished": "2026-06-22T19:56:56.776Z", "dateUpdated": "2026-08-28T12:04:25.625Z" }, "containers": { "cna": { "title": "Jupyter Server: Stored XSS in `NbconvertFileHandler` / `NbconvertPostHandler` via missing `sandbox` CSP", "problemTypes": [ { "descriptions": [ { "cweId": "CWE-79", "lang": "en", "description": "CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')", "type": "CWE" } ] }, { "descriptions": [ { "cweId": "CWE-1021", "lang": "en", "description": "CWE-1021: Improper Restriction of Rendered UI Layers or Frames", "type": "CWE" } ] } ], "metrics": [ { "cvssV4_0": { "attackVector": "NETWORK", "attackComplexity": "LOW", "attackRequirements": "NONE", "privilegesRequired": "LOW", "userInteraction": "ACTIVE", "vulnConfidentialityImpact": "HIGH", "vulnIntegrityImpact": "HIGH", "vulnAvailabilityImpact": "HIGH", "subConfidentialityImpact": "HIGH", "subIntegrityImpact": "HIGH", "subAvailabilityImpact": "HIGH", "baseScore": 9.3, "baseSeverity": "CRITICAL", "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:A/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H", "version": "4.0" } } ], "references": [ { "name": "https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-fcw5-x6j4-ccmp", "tags": [ "x_refsource_CONFIRM" ], "url": "https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-fcw5-x6j4-ccmp" }, { "name": "https://github.com/jupyter-server/jupyter_server/commit/6cbee8d65e71abac851c4492fea987ad080580bd", "tags": [ "x_refsource_MISC" ], "url": "https://github.com/jupyter-server/jupyter_server/commit/6cbee8d65e71abac851c4492fea987ad080580bd" } ], "affected": [ { "vendor": "jupyter-server", "product": "jupyter_server", "versions": [ { "version": "< 2.20", "status": "affected" } ] } ], "providerMetadata": { "orgId": "a0819718-46f1-4df5-94e2-005712e83aaa", "shortName": "GitHub_M", "dateUpdated": "2026-06-22T19:56:56.776Z" }, "descriptions": [ { "lang": "en", "value": "Jupyter Server is the backend for Jupyter web applications. Prior to 2.20, the nbconvert HTTP handlers in jupyter_server render user-authored notebook HTML under the Jupyter origin without a sandbox directive in their Content-Security-Policy. Combined with nbconvert.HTMLExporter's default non-sanitizing behavior, a notebook carrying an HTML payload in a display_data output triggers stored XSS with cookie access, full /api/* authority, and kernel RCE. This vulnerability is fixed in 2.20." } ], "source": { "advisory": "GHSA-fcw5-x6j4-ccmp", "discovery": "UNKNOWN" } }, "adp": [ { "metrics": [ { "other": { "type": "ssvc", "content": { "timestamp": "2026-06-23T12:15:20.487628Z", "id": "CVE-2026-44727", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "role": "CISA Coordinator", "version": "2.0.3" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2026-06-23T12:15:27.263Z" } }, { "affected": [ { "collectionURL": "https://catalog.redhat.com/software/containers/", "cpes": [ "cpe:/a:redhat:migration_toolkit_applications:8.2::el9" ], "defaultStatus": "affected", "packageName": "mta/mta-solution-server-rhel9", "product": "Red Hat Migration Toolkit for Applications 8.2", "vendor": "Red Hat", "versions": [ { "lessThan": "*", "status": "unaffected", "version": "1784109883", "versionType": 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The nbconvert HTTP handlers in Jupyter Server render user-authored notebook HTML without a sandbox directive in their Content-Security-Policy. This, combined with nbconvert.HTMLExporter's default non-sanitizing behavior, allows a notebook containing an HTML payload to trigger a stored Cross-Site Scripting (XSS) vulnerability. A remote attacker could exploit this to gain cookie access, full API authority, and achieve kernel Remote Code Execution (RCE)." } ], "metrics": [ { "other": { "content": { "namespace": "https://access.redhat.com/security/updates/classification/", "value": "Important" }, "type": "Red Hat severity rating" } }, { "cvssV3_1": { "attackComplexity": "LOW", "attackVector": "NETWORK", "availabilityImpact": "HIGH", "baseScore": 9, "baseSeverity": "CRITICAL", "confidentialityImpact": "HIGH", "integrityImpact": "HIGH", "privilegesRequired": "LOW", "scope": "CHANGED", "userInteraction": "REQUIRED", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:H/I:H/A:H", "version": "3.1" }, "format": "CVSS" } ], "problemTypes": [ { "descriptions": [ { "cweId": "CWE-79", "description": "Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')", "lang": "en", "type": "CWE" } ] } ], "references": [ { "tags": [ "vdb-entry", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/security/cve/CVE-2026-44727" }, { "name": "RHBZ#2491516", "tags": [ "issue-tracking", "x_refsource_REDHAT" ], "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2491516" }, { "tags": [ "x_sadp-csaf-vex" ], "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-44727.json" }, { "tags": [ "vendor-advisory", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/errata/RHSA-2026:43038" }, { "tags": [ "vendor-advisory", "x_refsource_REDHAT" ], "url": "https://access.redhat.com/errata/RHSA-2026:60520" } ], "solutions": [ { "lang": "en", "value": "RHSA-2026:43038: Red Hat Migration Toolkit for Applications 8.2" }, { "lang": "en", "value": "RHSA-2026:60520: Red Hat OpenShift AI 3.4" } ], "timeline": [ { "lang": "en", "time": "2026-06-22T21:00:50.127Z", "value": "Reported to Red Hat." }, { "lang": "en", "time": "2026-06-22T19:56:56.776Z", "value": "Made public." } ], "title": "jupyter-server: Jupyter Server: Remote Code Execution via stored Cross-Site Scripting in nbconvert handlers", "x_adpType": "supplier", "x_generator": { "engine": "sadp-cli 1.0.0" }, "providerMetadata": { "orgId": "0b0ca135-0b70-47e7-9f44-1890c2a1c46c", "shortName": "redhat-SADP", "dateUpdated": "2026-08-28T12:04:25.625Z" } } ] } }