high
8.5
CWE
20
Advisory Published
CVE Published
CVE Published
Updated

CVE-2020-25717: Input Validation

First published: Wed Nov 03 2021(Updated: )

A flaw was found in the way Samba maps domain users to local users. An authenticated attacker could use this flaw to cause possible privilege escalation.

Credit: secalert@redhat.com secalert@redhat.com secalert@redhat.com

Affected SoftwareAffected VersionHow to fix
Samba Samba>=3.0.0<4.13.14
Samba Samba>=4.14.0<4.14.10
Samba Samba>=4.15.0<4.15.2
Debian Debian Linux=9.0
Debian Debian Linux=10.0
Fedoraproject Fedora=33
Fedoraproject Fedora=34
Fedoraproject Fedora=35
Redhat Codeready Linux Builder
Redhat Gluster Storage=3.0
Redhat Gluster Storage=3.5
Redhat Openstack=13
Redhat Openstack=16.1
Redhat Openstack=16.2
Redhat Virtualization=4.0
Redhat Virtualization Host=4.0
Redhat Enterprise Linux=7.0
Redhat Enterprise Linux=8.0
Redhat Enterprise Linux Desktop=7.0
Redhat Enterprise Linux Eus=8.2
Redhat Enterprise Linux Eus=8.4
Redhat Enterprise Linux For Ibm Z Systems=7.0
Redhat Enterprise Linux For Ibm Z Systems=8.0
Redhat Enterprise Linux For Ibm Z Systems Eus=8.2
Redhat Enterprise Linux For Ibm Z Systems Eus=8.4
Redhat Enterprise Linux For Power Big Endian=7.0
Redhat Enterprise Linux For Power Little Endian=7.0
Redhat Enterprise Linux For Power Little Endian=8.0
Redhat Enterprise Linux For Power Little Endian Eus=8.2
Redhat Enterprise Linux For Power Little Endian Eus=8.4
Redhat Enterprise Linux For Scientific Computing=7.0
Redhat Enterprise Linux Resilient Storage=7.0
Redhat Enterprise Linux Server=7.0
Redhat Enterprise Linux Server Aus=8.2
Redhat Enterprise Linux Server Aus=8.4
Redhat Enterprise Linux Server Tus=8.4
Redhat Enterprise Linux Server Update Services For Sap Solutions=8.2
Redhat Enterprise Linux Server Update Services For Sap Solutions=8.4
Redhat Enterprise Linux Tus=8.2
Redhat Enterprise Linux Workstation=7.0
Canonical Ubuntu Linux=18.04
Canonical Ubuntu Linux=20.04
Canonical Ubuntu Linux=21.04
Canonical Ubuntu Linux=21.10
redhat/samba<0:4.10.16-17.el7_9
0:4.10.16-17.el7_9
redhat/samba<0:4.14.5-7.el8_5
0:4.14.5-7.el8_5
redhat/samba<0:4.11.2-18.el8_2
0:4.11.2-18.el8_2
redhat/samba<0:4.13.3-8.el8_4
0:4.13.3-8.el8_4
redhat/samba<0:4.11.6-114.el7
0:4.11.6-114.el7
redhat/samba<0:4.14.5-204.el8
0:4.14.5-204.el8
redhat/redhat-virtualization-host<0:4.3.21-20220126.0.el7_9
0:4.3.21-20220126.0.el7_9
redhat/samba<4.15.2
4.15.2
redhat/samba<4.14.10
4.14.10
redhat/samba<4.13.14
4.13.14
debian/samba
2:4.13.13+dfsg-1~deb11u6
2:4.17.12+dfsg-0+deb12u1
2:4.21.1+dfsg-2

Remedy

https://bugzilla.redhat.com/show_bug.cgi?id=2019672

Remedy

Setting "gensec:require_pac=true" in the smb.conf makes, due to a cache prime in winbind, the DOMAIN\user lookup succeed, provided nss_winbind is in use, 'winbind use default domain = no' (the default) and no error paths are hit. It would be prudent to pre-create disabled users in Active Directory matching on all privileged names not held in Active Directory, eg ~~~ samba-tool user add root -H ldap://$SERVER -U$USERNAME%$PASSWORD --random-password samba-tool user add ubuntu -H ldap://$SERVER -U$USERNAME%$PASSWORD --random-password ~~~ (repeat for eg all system users under 1000 in /etc/passwd or special to any other AD-connected services, eg perhaps "admin" for a web-app)

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