{"id":"CVE-2026-40110","aliases":["ALPINE-CVE-2026-40110","DEBIAN-CVE-2026-40110","EUVD-2026-27510","GHSA-24qx-w28j-9m6p","OESA-2026-4080","OESA-2026-4164","OESA-2026-4165","PYSEC-2026-2187","UBUNTU-CVE-2026-40110","openSUSE-SU-2026:10710-1"],"status":"published","title":"jupyter-server CORS origin validation bypass via unanchored regex in allow_origin_pat","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.","severity":{"version":"4.0","score":7.6,"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","level":"high","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-11","score":0.00313,"percentile":0.2452,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-625","CWE-777"],"published":"2026-05-05T16:54:31Z","modified":"2026-11-03T06:33:02Z","fixes":[{"ecosystem":"PyPI","package":"jupyter-server","fixed_in":["2.18.0"],"sources":["ghsa","osv"]},{"ecosystem":"Alpine:v3.24","package":"jupyter-server","fixed_in":["2.18.2-r0"],"sources":["osv"]},{"ecosystem":"Debian:14","package":"jupyter-server","fixed_in":["2.20.0-1"],"sources":["osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"jupyter-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"last_affected":"2.17.0"},{"fixed":"2.18.0"}]}]},{"source":"osv","ecosystem":"Alpine:v3.24","package":"jupyter-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.18.2-r0"}]}]},{"source":"osv","ecosystem":"Debian:12","package":"jupyter-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.23.3-1","1.23.3-2","2.14.0-1","2.14.2-1","2.14.2-2","2.14.2-3","2.14.2-4","2.14.2-5","2.15.0-1","2.17.0-1","2.20.0-1","2.20.0-2","2.20.0-3","2.9.1-1"]},{"source":"osv","ecosystem":"Debian:13","package":"jupyter-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.15.0-1","2.17.0-1","2.20.0-1","2.20.0-2","2.20.0-3"]},{"source":"osv","ecosystem":"Debian:14","package":"jupyter-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.20.0-1"}]}],"versions":["2.15.0-1","2.17.0-1"]},{"source":"osv","ecosystem":"PyPI","package":"jupyter-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.18.0"}]}],"versions":["0.0.0","0.0.1","0.0.2","0.0.3","0.0.4","0.0.5","0.1.0","0.1.1","0.2.0","0.2.1","0.3.0","1.0.0","1.0.0rc0","1.0.0rc1","1.0.0rc10","1.0.0rc11","1.0.0rc12","1.0.0rc13","1.0.0rc14","1.0.0rc15","1.0.0rc16","1.0.0rc2","1.0.0rc3","1.0.0rc4","1.0.0rc5","1.0.0rc6","1.0.0rc7","1.0.0rc8","1.0.0rc9","1.0.1","1.0.10","1.0.11","1.0.2","1.0.3","1.0.4","1.0.5","1.0.6","1.0.7","1.0.8","1.0.9","1.1.0","1.1.1","1.1.2","1.1.3","1.1.4","1.10.0","1.10.1","1.10.2","1.11.0","1.11.1","1.11.2","1.12.0","1.12.1","1.13.0","1.13.1","1.13.2","1.13.3","1.13.4","1.13.5","1.15.0","1.15.1","1.15.2","1.15.3","1.15.4","1.15.5","1.15.6","1.16.0","1.17.0","1.17.1","1.18.0","1.18.1","1.19.0","1.19.1","1.2.0","1.2.1","1.2.2","1.2.3","1.21.0","1.23.0","1.23.1","1.23.2","1.23.3","1.23.4","1.23.5","1.23.6","1.24.0","1.3.0","1.4.0","1.4.1","1.5.0","1.5.1","1.6.0","1.6.1","1.6.2","1.6.3","1.6.4","1.7.0","1.7.0a1","1.7.0a2","1.8.0","1.9.0","2.0.0","2.0.0a0","2.0.0a1","2.0.0a2","2.0.0b0","2.0.0b1","2.0.0rc0","2.0.0rc1","2.0.0rc2","2.0.0rc3","2.0.0rc4","2.0.0rc5","2.0.0rc6","2.0.0rc7","2.0.0rc8","2.0.1","2.0.2","2.0.3","2.0.4","2.0.5","2.0.6","2.0.7","2.1.0","2.10.0","2.10.1","2.11.0","2.11.1","2.11.2","2.12.0","2.12.1","2.12.2","2.12.3","2.12.4","2.12.5","2.13.0","2.14.0","2.14.1","2.14.2","2.15.0","2.16.0","2.17.0","2.2.0","2.2.1","2.3.0","2.4.0","2.5.0","2.6.0","2.7.0","2.7.1","2.7.2","2.7.3","2.8.0","2.9.0","2.9.1"]},{"source":"osv","ecosystem":"openEuler:24.03-LTS-SP4","package":"python-jupyter-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.13.0-3.oe2403sp4"}]}],"bundled":4},{"source":"osv","ecosystem":"openEuler:24.03-LTS-SP1","package":"python-jupyter-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.13.0-4.oe2403sp1"}]}],"bundled":4},{"source":"osv","ecosystem":"openEuler:24.03-LTS-SP3","package":"python-jupyter-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.13.0-4.oe2403sp3"}]}],"bundled":4},{"source":"osv","ecosystem":"PyPI","package":"jupyter-server","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.18.0"}]}],"versions":["0.0.0","0.0.1","0.0.2","0.0.3","0.0.4","0.0.5","0.1.0","0.1.1","0.2.0","0.2.1","0.3.0","1.0.0","1.0.0rc0","1.0.0rc1","1.0.0rc10","1.0.0rc11","1.0.0rc12","1.0.0rc13","1.0.0rc14","1.0.0rc15","1.0.0rc16","1.0.0rc2","1.0.0rc3","1.0.0rc4","1.0.0rc5","1.0.0rc6","1.0.0rc7","1.0.0rc8","1.0.0rc9","1.0.1","1.0.10","1.0.11","1.0.2","1.0.3","1.0.4","1.0.5","1.0.6","1.0.7","1.0.8","1.0.9","1.1.0","1.1.1","1.1.2","1.1.3","1.1.4","1.10.0","1.10.1","1.10.2","1.11.0","1.11.1","1.11.2","1.12.0","1.12.1","1.13.0","1.13.1","1.13.2","1.13.3","1.13.4","1.13.5","1.15.0","1.15.1","1.15.2","1.15.3","1.15.4","1.15.5","1.15.6","1.16.0","1.17.0","1.17.1","1.18.0","1.18.1","1.19.0","1.19.1","1.2.0","1.2.1","1.2.2","1.2.3","1.21.0","1.23.0","1.23.1","1.23.2","1.23.3","1.23.4","1.23.5","1.23.6","1.24.0","1.3.0","1.4.0","1.4.1","1.5.0","1.5.1","1.6.0","1.6.1","1.6.2","1.6.3","1.6.4","1.7.0","1.7.0a1","1.7.0a2","1.8.0","1.9.0","2.0.0","2.0.0a0","2.0.0a1","2.0.0a2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hat","product":"red hat migration toolkit for applications 8.2"},{"vendor":"red hat","product":"red hat openshift ai (rhoai)"}],"references":[{"url":"https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-24qx-w28j-9m6p","tags":["x_refsource_CONFIRM","Mitigation","Patch","Vendor Advisory","advisory","web","fix","report"]},{"url":"https://github.com/jupyter-server/jupyter_server/pull/603","tags":["x_refsource_MISC","Issue Tracking","fix","web","report"]},{"url":"https://github.com/jupyter-server/jupyter_server/commit/057869a327c46730afede3eab0ca2d2e3e74acea","tags":["x_refsource_MISC","Patch","fix","web","report"]},{"url":"https://github.com/jupyter-server/jupyter_server/commit/49b34392feaa97735b3b777e3baf8f22f2a14ed8","tags":["x_refsource_MISC","Patch","fix","web","report"]},{"url":"https://access.redhat.com/security/cve/CVE-2026-40110","tags":["vdb-entry","x_refsource_REDHAT","advisory","web"]},{"url":"https://bugzilla.redhat.com/show_bug.cgi?id=2466912","tags":["issue-tracking","x_refsource_REDHAT","report","web"]},{"url":"https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-40110.json","tags":["x_sadp-csaf-vex","web"]},{"url":"https://access.redhat.com/errata/RHSA-2026:43038","tags":["vendor-advisory","x_refsource_REDHAT","advisory","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-40110","tags":["advisory"]},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/jupyter-server/PYSEC-2026-2187.yaml","tags":["web"]},{"url":"https://github.com/advisories/GHSA-24qx-w28j-9m6p"},{"url":"https://security.alpinelinux.org/vuln/CVE-2026-40110","tags":["advisory"]},{"url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/40xxx/CVE-2026-40110.json","tags":["advisory"]},{"url":"https://security-tracker.debian.org/tracker/CVE-2026-40110","tags":["advisory"]},{"url":"https://github.com/jupyter-server/jupyter_server","tags":["package"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-4080","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2025-61669","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-35397","tags":["advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-40934","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-4164","tags":["advisory"]},{"url":"https://www.openeuler.org/zh/security/security-bulletins/detail/?id=openEuler-SA-2026-4165","tags":["advisory"]},{"url":"https://ubuntu.com/security/CVE-2026-40110","tags":["report"]},{"url":"https://www.cve.org/CVERecord?id=CVE-2026-40110","tags":["report"]},{"url":"","tags":["advisory"]},{"url":"https://www.suse.com/security/cve/CVE-2025-61669","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-35397","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-40110","tags":["web"]},{"url":"https://www.suse.com/security/cve/CVE-2026-40934","tags":["web"]}],"sources":{"cve":[{"id":"CVE-2026-40110","title":"jupyter-server CORS origin validation bypass via unanchored regex in allow_origin_pat","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.","status":"published","published":"2026-05-05T21:29:31.323Z","modified":"2026-07-22T12:08:40.428Z","cvss":[{"version":"4.0","score":7.6,"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","level":"high","assessor":"cna"},{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N","level":"high","assessor":"adp"}],"cwes":["CWE-777","CWE-625"],"updated_at":"2026-11-02T13:43:11.445168Z"}],"euvd":[{"id":"EUVD-2026-27510","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.","status":"published","published":"2026-05-05T21:29:31Z","modified":"2026-07-22T12:08:40Z","cvss":[{"version":"4.0","score":7.6,"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","level":"high"}],"updated_at":"2026-11-02T18:19:46.900828Z"}],"ghsa":[{"id":"GHSA-24qx-w28j-9m6p","title":"Jupyter Server has a  CORS Origin Validation Bypass via `re.match()` in `allow_origin_pat`","description":"Jupyter Server uses `re.match()` to validate the Origin header against the `allow_origin_pat` configuration.\n\nSince `re.match()` only anchors at the start of the string, an attacker who controls a domain like `http://trusted.example.com.evil.com/` passes validation against a pattern intended to match only `trusted.example.com`.\n\n### Impact\n\n\u003c=2.17.0\n\n### Patches\n\n057869a327c46730afede3eab0ca2d2e3e74acea, 49b34392feaa97735b3b777e3baf8f22f2a14ed8 \n\n### Workarounds\n\nWrap your `allow_origin_pat` value with `^` and `$`\n\n### References\n\nhttps://github.com/jupyter-server/jupyter_server/pull/603\nhttps://docs.python.org/3/library/re.html#re.fullmatch\nhttps://docs.python.org/3/library/re.html#re.match","status":"published","published":"2026-05-05T16:54:31Z","modified":"2026-07-31T20:27:12Z","cvss":[{"version":"4.0","score":7.6,"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","level":"high"}],"cwes":["CWE-625","CWE-777"],"updated_at":"2026-11-02T14:40:55.903445Z"}],"nvd":[{"id":"CVE-2026-40110","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.","status":"published","published":"2026-05-05T22:16:00.663Z","modified":"2026-07-24T21:10:00.143Z","cvss":[{"version":"4.0","score":7.6,"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","level":"high","assessor":"secondary"},{"version":"3.1","score":7.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N","level":"high","assessor":"primary"},{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N","level":"high","assessor":"secondary"}],"cwes":["CWE-777","CWE-625"],"updated_at":"2026-11-02T14:12:17.418622Z"}],"osv":[{"id":"ALPINE-CVE-2026-40110","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.","status":"published","published":"2026-05-05T22:16:00.663Z","modified":"2026-11-03T06:33:02.660413663Z","cvss":[{"version":"3.1","score":7.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N","level":"high"}],"updated_at":"2026-11-03T07:15:53.944853Z"},{"id":"CVE-2026-40110","title":"jupyter-server CORS origin validation bypass via unanchored regex in allow_origin_pat","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.","status":"published","published":"2026-05-05T21:29:31.323Z","modified":"2026-10-28T02:31:04.006921127Z","cvss":[{"version":"4.0","score":7.6,"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","level":"high"}],"cwes":["CWE-777"],"updated_at":"2026-11-02T15:45:03.040464Z"},{"id":"DEBIAN-CVE-2026-40110","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.","status":"published","published":"2026-05-05T22:16:00.663Z","modified":"2026-10-01T03:02:39.908197108Z","cvss":[{"version":"3.1","score":7.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T15:45:54.892385Z"},{"id":"GHSA-24qx-w28j-9m6p","title":"Jupyter Server has a  CORS Origin Validation Bypass via `re.match()` in `allow_origin_pat`","description":"Jupyter Server uses `re.match()` to validate the Origin header against the `allow_origin_pat` configuration.\n\nSince `re.match()` only anchors at the start of the string, an attacker who controls a domain like `http://trusted.example.com.evil.com/` passes validation against a pattern intended to match only `trusted.example.com`.\n\n### Impact\n\n\u003c=2.17.0\n\n### Patches\n\n057869a327c46730afede3eab0ca2d2e3e74acea, 49b34392feaa97735b3b777e3baf8f22f2a14ed8 \n\n### Workarounds\n\nWrap your `allow_origin_pat` value with `^` and `$`\n\n### References\n\nhttps://github.com/jupyter-server/jupyter_server/pull/603\nhttps://docs.python.org/3/library/re.html#re.fullmatch\nhttps://docs.python.org/3/library/re.html#re.match","status":"published","published":"2026-05-05T16:54:31Z","modified":"2026-09-10T03:50:45.011553229Z","cvss":[{"version":"4.0","score":7.6,"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","level":"high"}],"cwes":["CWE-625","CWE-777"],"updated_at":"2026-11-02T15:46:33.956911Z"},{"id":"OESA-2026-4080","title":"python-jupyter-server security update","description":"The backend for Jupyter web applications\r\n\r\nSecurity Fix(es):\n\nJupyter Server is the backend for Jupyter web applications. In jupyter_server versions through 2.17.0, the next query parameter in the login flow is insufficiently validated in `LoginFormHandler._redirect_safe()`, which allows redirects to arbitrary external domains via values such as `///example.com`. An attacker can use a crafted login URL to redirect users to a malicious site and facilitate phishing attacks. This issue is fixed in version 2.18.0.(CVE-2025-61669)\n\nJupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, a path traversal vulnerability in the REST API allows an authenticated user to escape the configured root_dir and access sibling directories whose names begin with the same prefix as the root_dir. For example, with a root_dir named \u0026quot;test\u0026quot;, the API permits access to a sibling directory named \u0026quot;testtest\u0026quot; through a crafted request to the /api/contents endpoint using encoded path components. An attacker can read, write, and delete files in affected sibling directories. Multi-tenant deployments using predictable naming schemes are particularly at risk, as a user with a directory named \u0026quot;user1\u0026quot; could access directories for user10 through user19 and beyond. A user who can choose a single-character folder name could gain access to a significant number of sibling directories. \n\nVersion 2.18.0 contains a fix. As a workaround, ensure folder names do not share a common prefix with any sibling directory.(CVE-2026-35397)\n\nJupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the Origin header validation uses Python\u0026apos;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.(CVE-2026-40110)\n\nJupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the secret used to sign authentication cookies is persisted to a static file at ~/.local/share/jupyter/runtime/jupyter_cookie_secret and is never rotated when a user changes their password. After a password reset and server restart, any previously issued authentication cookie remains cryptographically valid because the signing key has not changed. An attacker who has captured a session cookie through any means retains full authenticated access to the server regardless of subsequent password changes. This affects deployments using password-based authentication, particularly shared or public-facing servers where credential rotation is expected to revoke existing sessions. This issue has been fixed in version 2.18.0.(CVE-2026-40934)","status":"published","published":"2026-09-25T01:28:10Z","modified":"2026-09-25T01:45:10.359500693Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T15:52:47.643553Z"},{"id":"OESA-2026-4164","title":"python-jupyter-server security update","description":"The backend for Jupyter web applications\r\n\r\nSecurity Fix(es):\n\nJupyter Server is the backend for Jupyter web applications. In jupyter_server versions through 2.17.0, the next query parameter in the login flow is insufficiently validated in `LoginFormHandler._redirect_safe()`, which allows redirects to arbitrary external domains via values such as `///example.com`. An attacker can use a crafted login URL to redirect users to a malicious site and facilitate phishing attacks. This issue is fixed in version 2.18.0.(CVE-2025-61669)\n\nJupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, a path traversal vulnerability in the REST API allows an authenticated user to escape the configured root_dir and access sibling directories whose names begin with the same prefix as the root_dir. For example, with a root_dir named \u0026quot;test\u0026quot;, the API permits access to a sibling directory named \u0026quot;testtest\u0026quot; through a crafted request to the /api/contents endpoint using encoded path components. An attacker can read, write, and delete files in affected sibling directories. Multi-tenant deployments using predictable naming schemes are particularly at risk, as a user with a directory named \u0026quot;user1\u0026quot; could access directories for user10 through user19 and beyond. A user who can choose a single-character folder name could gain access to a significant number of sibling directories. \n\nVersion 2.18.0 contains a fix. As a workaround, ensure folder names do not share a common prefix with any sibling directory.(CVE-2026-35397)\n\nJupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the Origin header validation uses Python\u0026apos;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.(CVE-2026-40110)\n\nJupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the secret used to sign authentication cookies is persisted to a static file at ~/.local/share/jupyter/runtime/jupyter_cookie_secret and is never rotated when a user changes their password. After a password reset and server restart, any previously issued authentication cookie remains cryptographically valid because the signing key has not changed. An attacker who has captured a session cookie through any means retains full authenticated access to the server regardless of subsequent password changes. This affects deployments using password-based authentication, particularly shared or public-facing servers where credential rotation is expected to revoke existing sessions. This issue has been fixed in version 2.18.0.(CVE-2026-40934)","status":"published","published":"2026-09-30T13:47:13Z","modified":"2026-10-01T02:00:06.084650494Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T15:52:47.643553Z"},{"id":"OESA-2026-4165","title":"python-jupyter-server security update","description":"The backend for Jupyter web applications\r\n\r\nSecurity Fix(es):\n\nJupyter Server is the backend for Jupyter web applications. In jupyter_server versions through 2.17.0, the next query parameter in the login flow is insufficiently validated in `LoginFormHandler._redirect_safe()`, which allows redirects to arbitrary external domains via values such as `///example.com`. An attacker can use a crafted login URL to redirect users to a malicious site and facilitate phishing attacks. This issue is fixed in version 2.18.0.(CVE-2025-61669)\n\nJupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, a path traversal vulnerability in the REST API allows an authenticated user to escape the configured root_dir and access sibling directories whose names begin with the same prefix as the root_dir. For example, with a root_dir named \u0026quot;test\u0026quot;, the API permits access to a sibling directory named \u0026quot;testtest\u0026quot; through a crafted request to the /api/contents endpoint using encoded path components. An attacker can read, write, and delete files in affected sibling directories. Multi-tenant deployments using predictable naming schemes are particularly at risk, as a user with a directory named \u0026quot;user1\u0026quot; could access directories for user10 through user19 and beyond. A user who can choose a single-character folder name could gain access to a significant number of sibling directories. \n\nVersion 2.18.0 contains a fix. As a workaround, ensure folder names do not share a common prefix with any sibling directory.(CVE-2026-35397)\n\nJupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the Origin header validation uses Python\u0026apos;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.(CVE-2026-40110)\n\nJupyter Server is the backend for Jupyter web applications. In versions 2.17.0 and earlier, the secret used to sign authentication cookies is persisted to a static file at ~/.local/share/jupyter/runtime/jupyter_cookie_secret and is never rotated when a user changes their password. After a password reset and server restart, any previously issued authentication cookie remains cryptographically valid because the signing key has not changed. An attacker who has captured a session cookie through any means retains full authenticated access to the server regardless of subsequent password changes. This affects deployments using password-based authentication, particularly shared or public-facing servers where credential rotation is expected to revoke existing sessions. This issue has been fixed in version 2.18.0.(CVE-2026-40934)","status":"published","published":"2026-09-30T13:47:13Z","modified":"2026-10-01T02:00:05.375706013Z","cvss":[{"version":"3.1","score":8.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","level":"high"}],"updated_at":"2026-11-02T15:52:47.643553Z"},{"id":"PYSEC-2026-2187","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.","status":"published","published":"2026-05-05T22:16:00.663Z","modified":"2026-07-13T07:15:34.116347312Z","cvss":[{"version":"3.1","score":7.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T15:52:55.537808Z"},{"id":"UBUNTU-CVE-2026-40110","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.","status":"published","published":"2026-05-05T22:16:00Z","modified":"2026-10-17T13:00:04.572035504Z","cvss":[{"version":"4.0","score":7.6,"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","level":"high"},{"version":"3.1","score":7.1,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:L/A:N","level":"high"},{"version":"3.1","score":7.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:N","level":"high"}],"updated_at":"2026-11-02T16:56:16.686388Z"},{"id":"openSUSE-SU-2026:10710-1","title":"python311-jupyter-server-2.18.1-1.1 on GA media","description":"These are all security issues fixed in the python311-jupyter-server-2.18.1-1.1 package on the GA media of openSUSE Tumbleweed.","status":"published","published":"2026-05-06T00:00:00Z","modified":"2026-05-07T08:47:56.034639Z","updated_at":"2026-11-02T16:58:38.415593Z"}]}}