A vulnerability was discovered in Samba, where the flaw allows SMB clients to truncate files, even with read-only permissions when the Samba VFS module "aclxattr" is configured with "aclxattr:ignore system acls = yes". The SMB protocol allows opening files when the client requests read-only access but then implicitly truncates the opened file to 0 bytes if the client specifies a separate OVERWRITE create disposition request. The issue arises in configurations that bypass kernel file system permissions checks, relying solely on Samba's permissions.
{ "availability": "No subscription required", "ubuntu_priority": "medium", "binaries": [ { "binary_name": "ctdb", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "ctdb-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "libnss-winbind", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "libnss-winbind-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "libpam-winbind", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "libpam-winbind-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "libsmbclient", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "libsmbclient-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "libsmbclient-dev", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "libwbclient-dev", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "libwbclient0", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "libwbclient0-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "python3-samba", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "python3-samba-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "registry-tools", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "registry-tools-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-common", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-common-bin", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-common-bin-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-dev", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-dsdb-modules", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-dsdb-modules-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-libs", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-libs-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-testsuite", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-testsuite-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-vfs-modules", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "samba-vfs-modules-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "smbclient", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "smbclient-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "winbind", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" }, { "binary_name": "winbind-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu0.20.04.6" } ] }
{ "availability": "No subscription required", "ubuntu_priority": "medium", "binaries": [ { "binary_name": "ctdb", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "ctdb-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "libnss-winbind", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "libnss-winbind-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "libpam-winbind", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "libpam-winbind-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "libsmbclient", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "libsmbclient-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "libsmbclient-dev", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "libwbclient-dev", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "libwbclient0", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "libwbclient0-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "python3-samba", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "python3-samba-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "registry-tools", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "registry-tools-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-common", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-common-bin", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-common-bin-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-dev", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-dsdb-modules", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-dsdb-modules-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-libs", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-libs-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-testsuite", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-testsuite-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-vfs-modules", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "samba-vfs-modules-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "smbclient", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "smbclient-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "winbind", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" }, { "binary_name": "winbind-dbgsym", "binary_version": "2:4.15.13+dfsg-0ubuntu1.5" } ] }
{ "availability": "No subscription required", "ubuntu_priority": "medium", "binaries": [ { "binary_name": "ctdb", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "ctdb-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "ldb-tools", "binary_version": "2:2.7.2+samba4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "ldb-tools-dbgsym", "binary_version": "2:2.7.2+samba4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libldb-dev", "binary_version": "2:2.7.2+samba4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libldb2", "binary_version": "2:2.7.2+samba4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libldb2-dbgsym", "binary_version": "2:2.7.2+samba4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libnss-winbind", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libnss-winbind-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libpam-winbind", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libpam-winbind-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libsmbclient", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libsmbclient-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libsmbclient-dev", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libwbclient-dev", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libwbclient0", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "libwbclient0-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "python3-ldb", "binary_version": "2:2.7.2+samba4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "python3-ldb-dbgsym", "binary_version": "2:2.7.2+samba4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "python3-ldb-dev", "binary_version": "2:2.7.2+samba4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "python3-samba", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "python3-samba-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "registry-tools", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "registry-tools-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-ad-dc", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-ad-provision", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-common", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-common-bin", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-common-bin-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-dev", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-dsdb-modules", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-dsdb-modules-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-libs", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-libs-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-testsuite", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-testsuite-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-vfs-modules", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "samba-vfs-modules-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "smbclient", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "smbclient-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "winbind", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" }, { "binary_name": "winbind-dbgsym", "binary_version": "2:4.18.6+dfsg-1ubuntu2.1" } ] }