{"id":"UBUNTU-CVE-2026-40934","details":"Jupyter 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.","modified":"2026-05-20T16:25:40.734826652Z","published":"2026-05-05T22:16:00Z","upstream":["CVE-2026-40934"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-40934"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-40934"},{"type":"REPORT","url":"https://github.com/jupyter-server/jupyter_server/security/advisories/GHSA-5mrq-x3x5-8v8f"}],"affected":[{"package":{"name":"jupyter-server","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/jupyter-server?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.2.2-1","1.13.1-1"],"ecosystem_specific":{"binaries":[{"binary_version":"1.13.1-1","binary_name":"jupyter-server"},{"binary_name":"python3-jupyter-server","binary_version":"1.13.1-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40934.json"}},{"package":{"name":"jupyter-server","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/jupyter-server?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["1.23.3-1","1.23.3-2"],"ecosystem_specific":{"binaries":[{"binary_version":"1.23.3-2","binary_name":"jupyter-server"},{"binary_version":"1.23.3-2","binary_name":"python3-jupyter-server"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40934.json"}},{"package":{"name":"jupyter-server","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/jupyter-server?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.14.2-5","2.15.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"jupyter-server","binary_version":"2.15.0-1"},{"binary_name":"python3-jupyter-server","binary_version":"2.15.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40934.json"}},{"package":{"name":"jupyter-server","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/jupyter-server?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.15.0-1","2.17.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"jupyter-server","binary_version":"2.17.0-1"},{"binary_name":"python3-jupyter-server","binary_version":"2.17.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-40934.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V4","score":"CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N"},{"type":"Ubuntu","score":"medium"}]}