{"id":"USN-4930-1","summary":"samba vulnerability","details":"Peter Eriksson discovered that Samba incorrectly handled certain negative\nidmap cache entries. This issue could result in certain users gaining\nunauthorized access to files, contrary to expected behaviour.\n","modified":"2026-04-22T10:27:50.001820Z","published":"2021-04-29T16:48:57Z","related":["UBUNTU-CVE-2021-20254"],"upstream":["CVE-2021-20254","UBUNTU-CVE-2021-20254"],"references":[{"type":"ADVISORY","url":"https://ubuntu.com/security/notices/USN-4930-1"},{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2021-20254"}],"affected":[{"package":{"name":"samba","ecosystem":"Ubuntu:16.04:LTS","purl":"pkg:deb/ubuntu/samba@2:4.3.11+dfsg-0ubuntu0.16.04.34?arch=source&distro=xenial"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2:4.3.11+dfsg-0ubuntu0.16.04.34"}]}],"versions":["2:4.1.17+dfsg-4ubuntu2","2:4.1.20+dfsg-1ubuntu1","2:4.1.20+dfsg-1ubuntu2","2:4.1.20+dfsg-1ubuntu3","2:4.1.20+dfsg-1ubuntu5","2:4.3.3+dfsg-1ubuntu1","2:4.3.3+dfsg-1ubuntu2","2:4.3.3+dfsg-1ubuntu3","2:4.3.6+dfsg-1ubuntu1","2:4.3.8+dfsg-0ubuntu1","2:4.3.9+dfsg-0ubuntu0.16.04.1","2:4.3.9+dfsg-0ubuntu0.16.04.2","2:4.3.9+dfsg-0ubuntu0.16.04.3","2:4.3.11+dfsg-0ubuntu0.16.04.1","2:4.3.11+dfsg-0ubuntu0.16.04.3","2:4.3.11+dfsg-0ubuntu0.16.04.5","2:4.3.11+dfsg-0ubuntu0.16.04.6","2:4.3.11+dfsg-0ubuntu0.16.04.7","2:4.3.11+dfsg-0ubuntu0.16.04.8","2:4.3.11+dfsg-0ubuntu0.16.04.9","2:4.3.11+dfsg-0ubuntu0.16.04.10","2:4.3.11+dfsg-0ubuntu0.16.04.11","2:4.3.11+dfsg-0ubuntu0.16.04.12","2:4.3.11+dfsg-0ubuntu0.16.04.13","2:4.3.11+dfsg-0ubuntu0.16.04.15","2:4.3.11+dfsg-0ubuntu0.16.04.16","2:4.3.11+dfsg-0ubuntu0.16.04.17","2:4.3.11+dfsg-0ubuntu0.16.04.18","2:4.3.11+dfsg-0ubuntu0.16.04.19","2:4.3.11+dfsg-0ubuntu0.16.04.20","2:4.3.11+dfsg-0ubuntu0.16.04.21","2:4.3.11+dfsg-0ubuntu0.16.04.23","2:4.3.11+dfsg-0ubuntu0.16.04.24","2:4.3.11+dfsg-0ubuntu0.16.04.25","2:4.3.11+dfsg-0ubuntu0.16.04.26","2:4.3.11+dfsg-0ubuntu0.16.04.27","2:4.3.11+dfsg-0ubuntu0.16.04.28","2:4.3.11+dfsg-0ubuntu0.16.04.29","2:4.3.11+dfsg-0ubuntu0.16.04.30","2:4.3.11+dfsg-0ubuntu0.16.04.31","2:4.3.11+dfsg-0ubuntu0.16.04.32"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"ctdb","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"libnss-winbind","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"libpam-winbind","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"libparse-pidl-perl","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"libsmbclient","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"libwbclient0","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"python-samba","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"registry-tools","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"samba","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"samba-common","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"samba-common-bin","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"samba-dsdb-modules","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"samba-libs","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"samba-testsuite","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"samba-vfs-modules","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"smbclient","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"},{"binary_name":"winbind","binary_version":"2:4.3.11+dfsg-0ubuntu0.16.04.34"}]},"database_specific":{"cves_map":{"cves":[{"id":"CVE-2021-20254","severity":[{"score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","type":"CVSS_V3"},{"score":"medium","type":"Ubuntu"}]}],"ecosystem":"Ubuntu:16.04:LTS"},"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-4930-1.json"}},{"package":{"name":"samba","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/samba@2:4.7.6+dfsg~ubuntu-0ubuntu2.23?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"}]}],"versions":["2:4.6.7+dfsg-1ubuntu3","2:4.7.1+dfsg-1ubuntu1","2:4.7.3+dfsg-1ubuntu1","2:4.7.4+dfsg-1ubuntu1","2:4.7.6+dfsg~ubuntu-0ubuntu1","2:4.7.6+dfsg~ubuntu-0ubuntu2","2:4.7.6+dfsg~ubuntu-0ubuntu2.2","2:4.7.6+dfsg~ubuntu-0ubuntu2.4","2:4.7.6+dfsg~ubuntu-0ubuntu2.5","2:4.7.6+dfsg~ubuntu-0ubuntu2.6","2:4.7.6+dfsg~ubuntu-0ubuntu2.7","2:4.7.6+dfsg~ubuntu-0ubuntu2.9","2:4.7.6+dfsg~ubuntu-0ubuntu2.10","2:4.7.6+dfsg~ubuntu-0ubuntu2.11","2:4.7.6+dfsg~ubuntu-0ubuntu2.13","2:4.7.6+dfsg~ubuntu-0ubuntu2.14","2:4.7.6+dfsg~ubuntu-0ubuntu2.15","2:4.7.6+dfsg~ubuntu-0ubuntu2.16","2:4.7.6+dfsg~ubuntu-0ubuntu2.17","2:4.7.6+dfsg~ubuntu-0ubuntu2.18","2:4.7.6+dfsg~ubuntu-0ubuntu2.19","2:4.7.6+dfsg~ubuntu-0ubuntu2.20","2:4.7.6+dfsg~ubuntu-0ubuntu2.21"],"ecosystem_specific":{"availability":"No subscription required","binaries":[{"binary_name":"ctdb","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"libnss-winbind","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"libpam-winbind","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"libparse-pidl-perl","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"libsmbclient","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"libwbclient0","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"python-samba","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"registry-tools","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"samba","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"samba-common","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"samba-common-bin","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"samba-dsdb-modules","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"samba-libs","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"samba-testsuite","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"samba-vfs-modules","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"smbclient","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"},{"binary_name":"winbind","binary_version":"2:4.7.6+dfsg~ubuntu-0ubuntu2.23"}]},"database_specific":{"cves_map":{"cves":[{"id":"CVE-2021-20254","severity":[{"score":"CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N","type":"CVSS_V3"},{"score":"medium","type":"Ubuntu"}]}],"ecosystem":"Ubuntu:18.04:LTS"},"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/usn/USN-4930-1.json"}},{"package":{"name":"samba","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/samba@2:4.11.6+dfsg-0ubuntu1.8?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2:4.11.6+dfsg-0ubuntu1.8"}]}],"versions":["2:4.10.7+dfsg-0ubuntu2","2:4.10.7+dfsg-0ubuntu3","2:4.11.1+dfsg-3ubuntu1","2:4.11.1+dfsg-3ubuntu2","2:4.11.1+dfsg-3ubuntu4","2:4.11.5+dfsg-1ubuntu1","2:4.11.5+dfsg-1ubuntu2","2:4.11.6+dfsg-0ubuntu1","2:4.11.6+dfsg-0ubuntu1.1","2:4.11.6+dfsg-0ubuntu1.2","2:4.11.6+dfsg-0ubuntu1.3","2:4.11.6+dfsg-0ubuntu1.4","2:4.11.6+dfsg-0ubuntu1.5","2:4.11.6+dfsg-0ubuntu1.6"],"ecosystem_specific":{"availability":"No 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