{"id":"UBUNTU-CVE-2018-20217","details":"A Reachable Assertion issue was discovered in the KDC in MIT Kerberos 5 (aka krb5) before 1.17. If an attacker can obtain a krbtgt ticket using an older encryption type (single-DES, triple-DES, or RC4), the attacker can crash the KDC by making an S4U2Self request.","modified":"2026-04-22T13:03:51.657579Z","published":"2018-12-26T21:29:00Z","related":["USN-5828-1"],"upstream":["CVE-2018-20217"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2018-20217"},{"type":"REPORT","url":"https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2KNHELH4YHNT6H2ESJWX2UIDXLBNGB2O/"},{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-5828-1"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2018-20217"}],"affected":[{"package":{"name":"krb5","ecosystem":"Ubuntu:Pro:14.04:LTS","purl":"pkg:deb/ubuntu/krb5@1.12+dfsg-2ubuntu5.4+esm1?arch=source&distro=trusty/esm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.12+dfsg-2ubuntu5.4+esm1"}]}],"versions":["1.10.1+dfsg-6.1ubuntu1","1.11.3+dfsg-3ubuntu2","1.12+dfsg-2ubuntu1","1.12+dfsg-2ubuntu2","1.12+dfsg-2ubuntu3","1.12+dfsg-2ubuntu4","1.12+dfsg-2ubuntu4.2","1.12+dfsg-2ubuntu5","1.12+dfsg-2ubuntu5.1","1.12+dfsg-2ubuntu5.2","1.12+dfsg-2ubuntu5.3","1.12+dfsg-2ubuntu5.4"],"ecosystem_specific":{"binaries":[{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"krb5-admin-server"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"krb5-gss-samples"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"krb5-kdc"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"krb5-kdc-ldap"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"krb5-locales"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"krb5-multidev"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"krb5-otp"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"krb5-pkinit"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"krb5-user"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"libgssapi-krb5-2"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"libgssrpc4"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"libk5crypto3"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"libkadm5clnt-mit9"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"libkadm5srv-mit8"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"libkadm5srv-mit9"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"libkdb5-7"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"libkrad0"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"libkrb5-3"},{"binary_version":"1.12+dfsg-2ubuntu5.4+esm1","binary_name":"libkrb5support0"}],"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2018/UBUNTU-CVE-2018-20217.json"}},{"package":{"name":"krb5","ecosystem":"Ubuntu:Pro:16.04:LTS","purl":"pkg:deb/ubuntu/krb5@1.13.2+dfsg-5ubuntu2.2+esm3?arch=source&distro=esm-infra/xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.13.2+dfsg-5ubuntu2.2+esm3"}]}],"versions":["1.13.2+dfsg-2","1.13.2+dfsg-3","1.13.2+dfsg-4","1.13.2+dfsg-5","1.13.2+dfsg-5ubuntu1","1.13.2+dfsg-5ubuntu2","1.13.2+dfsg-5ubuntu2.1","1.13.2+dfsg-5ubuntu2.1+esm1","1.13.2+dfsg-5ubuntu2.2"],"ecosystem_specific":{"binaries":[{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"krb5-admin-server"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"krb5-gss-samples"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"krb5-k5tls"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"krb5-kdc"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"krb5-kdc-ldap"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"krb5-locales"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"krb5-multidev"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"krb5-otp"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"krb5-pkinit"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"krb5-user"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"libgssapi-krb5-2"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"libgssrpc4"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"libk5crypto3"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"libkadm5clnt-mit9"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"libkadm5srv-mit9"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"libkdb5-8"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"libkrad0"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"libkrb5-3"},{"binary_version":"1.13.2+dfsg-5ubuntu2.2+esm3","binary_name":"libkrb5support0"}],"availability":"Available with Ubuntu Pro (Infra-only): https://ubuntu.com/pro"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2018/UBUNTU-CVE-2018-20217.json"}},{"package":{"name":"krb5","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/krb5@1.16-2ubuntu0.3?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.16-2ubuntu0.3"}]}],"versions":["1.15.1-2","1.16-2","1.16-2build1","1.16-2ubuntu0.1","1.16-2ubuntu0.2"],"ecosystem_specific":{"binaries":[{"binary_version":"1.16-2ubuntu0.3","binary_name":"krb5-admin-server"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"krb5-gss-samples"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"krb5-k5tls"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"krb5-kdc"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"krb5-kdc-ldap"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"krb5-kpropd"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"krb5-locales"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"krb5-multidev"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"krb5-otp"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"krb5-pkinit"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"krb5-user"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"libgssapi-krb5-2"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"libgssrpc4"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"libk5crypto3"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"libkadm5clnt-mit11"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"libkadm5srv-mit11"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"libkdb5-9"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"libkrad0"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"libkrb5-3"},{"binary_version":"1.16-2ubuntu0.3","binary_name":"libkrb5support0"}],"availability":"No subscription required"},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2018/UBUNTU-CVE-2018-20217.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V3","score":"CVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}