{"id":"UBUNTU-CVE-2021-39191","details":"mod_auth_openidc is an authentication/authorization module for the Apache 2.x HTTP server that functions as an OpenID Connect Relying Party, authenticating users against an OpenID Connect Provider. In versions prior to 2.4.9.4, the 3rd-party init SSO functionality of mod_auth_openidc was reported to be vulnerable to an open redirect attack by supplying a crafted URL in the `target_link_uri` parameter. A patch in version 2.4.9.4 made it so that the `OIDCRedirectURLsAllowed` setting must be applied to the `target_link_uri` parameter. There are no known workarounds aside from upgrading to a patched version.","modified":"2025-10-24T04:50:29Z","published":"2021-09-03T14:15:00Z","upstream":["CVE-2021-39191"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-39191"},{"type":"REPORT","url":"https://github.com/zmartzone/mod_auth_openidc/issues/672"},{"type":"REPORT","url":"https://github.com/zmartzone/mod_auth_openidc/commit/03e6bfb446f4e3f27c003d30d6a433e5dd8e2b3d"},{"type":"REPORT","url":"https://github.com/zmartzone/mod_auth_openidc/releases/tag/v2.4.9.4"},{"type":"REPORT","url":"https://github.com/zmartzone/mod_auth_openidc/security/advisories/GHSA-2pgf-8h6h-gqg2"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2021-39191"}],"affected":[{"package":{"name":"libapache2-mod-auth-openidc","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/libapache2-mod-auth-openidc@2.3.3-1build1?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.1.6-1","2.3.1-2","2.3.2-1","2.3.2-1build1","2.3.3-1build1"],"ecosystem_specific":{"binaries":[{"binary_name":"libapache2-mod-auth-openidc","binary_version":"2.3.3-1build1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-39191.json"}},{"package":{"name":"libapache2-mod-auth-openidc","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/libapache2-mod-auth-openidc@2.4.1-1?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2.3.10.2-1","2.4.0.4-1","2.4.1-1"],"ecosystem_specific":{"binaries":[{"binary_name":"libapache2-mod-auth-openidc","binary_version":"2.4.1-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2021/UBUNTU-CVE-2021-39191.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:N/I:L/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]}