title: Samba: smb clients can truncate files with read-only permissions
description: 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 "acl_xattr" is configured with "acl_xattr: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.
problem types: Incorrect Default Permissions
affected:
{
product: samba
vendor: n/a
versions:
version: 4.19.1, status: unaffected
version: 4.18.8, status: unaffected
version: 4.17.12, status: unaffected
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 8
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba
defaultStatus: affected
versions:
version: 0:4.18.6-2.el8_9, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:enterprise_linux:8::appstream, cpe:/a:redhat:enterprise_linux:8::crb, cpe:/o:redhat:enterprise_linux:8::baseos]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 8
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba
defaultStatus: affected
versions:
version: 0:4.18.6-2.el8_9, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:enterprise_linux:8::appstream, cpe:/a:redhat:enterprise_linux:8::crb, cpe:/o:redhat:enterprise_linux:8::baseos]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 8.6 Extended Update Support
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba
defaultStatus: affected
versions:
version: 0:4.15.5-13.el8_6, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:rhel_eus:8.6::crb, cpe:/a:redhat:rhel_eus:8.6::appstream, cpe:/o:redhat:rhel_eus:8.6::baseos, cpe:/o:redhat:enterprise_linux:8::hypervisor]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 8.8 Extended Update Support
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba
defaultStatus: affected
versions:
version: 0:4.17.5-4.el8_8, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/o:redhat:rhel_eus:8.8::baseos, cpe:/a:redhat:rhel_eus:8.8::appstream, cpe:/a:redhat:rhel_eus:8.8::crb]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 9
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba
defaultStatus: affected
versions:
version: 0:4.18.6-101.el9_3, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:enterprise_linux:9::resilientstorage, cpe:/a:redhat:enterprise_linux:9::appstream, cpe:/o:redhat:enterprise_linux:9::baseos, cpe:/a:redhat:enterprise_linux:9::crb]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 9
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba
defaultStatus: affected
versions:
version: 0:4.18.6-101.el9_3, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:enterprise_linux:9::resilientstorage, cpe:/a:redhat:enterprise_linux:9::appstream, cpe:/o:redhat:enterprise_linux:9::baseos, cpe:/a:redhat:enterprise_linux:9::crb]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 9.0 Extended Update Support
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba
defaultStatus: affected
versions:
version: 0:4.15.5-111.el9_0, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:rhel_eus:9.0::crb, cpe:/a:redhat:rhel_eus:9.0::appstream, cpe:/o:redhat:rhel_eus:9.0::baseos, cpe:/a:redhat:rhel_eus:9.0::resilientstorage]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 9.2 Extended Update Support
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba
defaultStatus: affected
versions:
version: 0:4.17.5-104.el9_2, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:rhel_eus:9.2::resilientstorage, cpe:/o:redhat:rhel_eus:9.2::baseos, cpe:/a:redhat:rhel_eus:9.2::crb, cpe:/a:redhat:rhel_eus:9.2::appstream]
}
{
vendor: Red Hat
product: Red Hat Virtualization 4 for Red Hat Enterprise Linux 8
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba
defaultStatus: affected
versions:
version: 0:4.15.5-13.el8_6, lessThan: *, versionType: rpm, status: unaffected
cpe: [cpe:/a:redhat:rhel_eus:8.6::crb, cpe:/a:redhat:rhel_eus:8.6::appstream, cpe:/o:redhat:rhel_eus:8.6::baseos, cpe:/o:redhat:enterprise_linux:8::hypervisor]
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 6
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba
defaultStatus: unknown
cpes: cpe:/o:redhat:enterprise_linux:6
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 6
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba4
defaultStatus: unknown
cpes: cpe:/o:redhat:enterprise_linux:6
}
{
vendor: Red Hat
product: Red Hat Enterprise Linux 7
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba
defaultStatus: unknown
cpes: cpe:/o:redhat:enterprise_linux:7
}
{
vendor: Red Hat
product: Red Hat Storage 3
collectionURL: https://access.redhat.com/downloads/content/package-browser/
packageName: samba
defaultStatus: affected
cpes: cpe:/a:redhat:storage:3
}
{
product: Fedora
vendor: Fedora
collectionURL: https://packages.fedoraproject.org/
packageName: samba
defaultStatus: affected
}
metrics:
other: [
content: {'value': 'Moderate', 'namespace': 'https://access.redhat.com/security/updates/classification/'}
type: Red Hat severity rating
]
workarounds: The vulnerability is most commonly associated with the "acl_xattr" module and can be mitigated by setting:
~~~
"acl_xattr:ignore system acls = no"
~~~
