Vulnerability CVE-2019-14870
Published: 2019-12-10   Modified: 2019-12-11

Description:
All Samba versions 4.x.x before 4.9.17, 4.10.x before 4.10.11 and 4.11.x before 4.11.3 have an issue, where the S4U (MS-SFU) Kerberos delegation model includes a feature allowing for a subset of clients to be opted out of constrained delegation in any way, either S4U2Self or regular Kerberos authentication, by forcing all tickets for these clients to be non-forwardable. In AD this is implemented by a user attribute delegation_not_allowed (aka not-delegated), which translates to disallow-forwardable. However the Samba AD DC does not do that for S4U2Self and does set the forwardable flag even if the impersonated client has the not-delegated flag set.

Type:

CWE-287

 (Improper Authentication)

CVSS2 => (AV:N/AC:L/Au:N/C:P/I:P/A:N)

CVSS Base Score
Impact Subscore
Exploitability Subscore
6.4/10
4.9/10
10/10
Exploit range
Attack complexity
Authentication
Remote
Low
No required
Confidentiality impact
Integrity impact
Availability impact
Partial
Partial
None
Affected software
Samba -> Samba 
Fedoraproject -> Fedora 
Canonical -> Ubuntu linux 

 References:
http://lists.opensuse.org/opensuse-security-announce/2019-12/msg00038.html
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2019-14870
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/PJH3ROOFYMOATD2UEPC47P5RPBDTY77E/
https://security.netapp.com/advisory/ntap-20191210-0002/
https://usn.ubuntu.com/4217-1/
https://usn.ubuntu.com/4217-2/
https://www.samba.org/samba/security/CVE-2019-14870.html
https://www.synology.com/security/advisory/Synology_SA_19_40
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