{"id":"UBUNTU-CVE-2021-23385","details":"This affects all versions of package Flask-Security. When using the get_post_logout_redirect and get_post_login_redirect functions, it is possible to bypass URL validation and redirect a user to an arbitrary URL by providing multiple back slashes such as \\\\\\evil.com/path. This vulnerability is only exploitable if an alternative WSGI server other than Werkzeug is used, or the default behaviour of Werkzeug is modified using 'autocorrect_location_header=False. **Note:** Flask-Security is not maintained anymore.","modified":"2026-01-30T00:32:38.081730Z","published":"2022-08-02T14:15:00Z","related":["USN-6792-1"],"upstream":["CVE-2021-23385"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-23385"},{"type":"REPORT","url":"https://security.snyk.io/vuln/SNYK-PYTHON-FLASKSECURITY-1293234"},{"type":"REPORT","url":"https://github.com/mattupstate/flask-security"},{"type":"REPORT","url":"https://snyk.io/blog/url-confusion-vulnerabilities/"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2021-23385"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-6792-1"}],"affected":[{"package":{"name":"flask-security","ecosystem":"Ubuntu:Pro:18.04:LTS","purl":"pkg:deb/ubuntu/flask-security@1.7.5-2ubuntu0.18.04.1~esm1?arch=source&distro=esm-apps/bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.7.5-2ubuntu0.18.04.1~esm1"}]}],"versions":["1.7.5-1","1.7.5-2"],"ecosystem_specific":{"availability":"Available with Ubuntu Pro: https://ubuntu.com/pro","binaries":[{"binary_version":"1.7.5-2ubuntu0.18.04.1~esm1","binary_name":"python3-flask-security"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-23385.json"}},{"package":{"name":"flask-security","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/flask-security@1.7.5-2ubuntu0.20.04.1?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.7.5-2ubuntu0.20.04.1"}]}],"versions":["1.7.5-2"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"python3-flask-security","binary_version":"1.7.5-2ubuntu0.20.04.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-23385.json"}},{"package":{"name":"flask-security","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/flask-security@4.0.0-1ubuntu0.1?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"4.0.0-1ubuntu0.1"}]}],"versions":["4.0.0-1"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"python3-flask-security","binary_version":"4.0.0-1ubuntu0.1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-23385.json"}}],"schema_version":"1.7.3","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]}