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
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
Samba>=3.0.0<4.13.14
Samba>=4.14.0<4.14.10
Samba>=4.15.0<4.15.2
Debian GNU/Linux=9.0
Debian GNU/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
Red Hat Enterprise Virtualization=4.0
redhat virtualization host=4.0
Red Hat Enterprise Linux=7.0
Red Hat 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
Red Hat 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
Ubuntu Linux=18.04
Ubuntu Linux=20.04
Ubuntu Linux=21.04
Ubuntu Linux=21.10
Debian=9.0
Debian=10.0
Fedora=33
Fedora=34
Fedora=35
GlusterFS=3.0
GlusterFS=3.5
Ubuntu=18.04
Ubuntu=20.04
Ubuntu=21.04
Ubuntu=21.10

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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Reference Links

Parent vulnerabilities

(Appears in the following advisories)

Frequently Asked Questions

  • What is the severity of CVE-2020-25717?

    CVE-2020-25717 is classified as a medium severity vulnerability as it allows for potential privilege escalation for authenticated attackers.

  • How do I fix CVE-2020-25717?

    To remediate CVE-2020-25717, you should update Samba to a patched version as specified in your vendor's advisory.

  • What systems are affected by CVE-2020-25717?

    CVE-2020-25717 affects various versions of Samba on Red Hat and Debian systems, including specific versions noted in the vulnerability advisory.

  • Is CVE-2020-25717 exploitable remotely?

    No, CVE-2020-25717 requires authenticated access to exploit, meaning an attacker must already have valid credentials.

  • What versions of Samba should I upgrade to mitigate CVE-2020-25717?

    To mitigate CVE-2020-25717, upgrade Samba to versions 4.10.16-17.el7_9, 4.14.5-7.el8_5, or later secure versions as indicated by your distribution.

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