Authentication flaw

2019-12-1023:15:00

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5.4 Medium

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

LOW

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

LOW

Integrity Impact

LOW

Availability Impact

NONE

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

5.2 Medium

AI Score

Confidence

High

6.4 Medium

CVSS2

Access Vector

NETWORK

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

NONE

AV:N/AC:L/Au:N/C:P/I:P/A:N

0.002 Low

EPSS

Percentile

63.7%

JSON

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.

CPENameOperatorVersion
ubuntu_linuxeq18.04
ubuntu_linuxeq19.04
ubuntu_linuxeq14.04
ubuntu_linuxeq19.10
ubuntu_linuxeq16.04
debian_linuxeq9.0
debian_linuxeq10.0
fedoraeq30
fedoraeq31
leapeq15.1

Name	Operator	Version
ubuntu_linux	eq	18.04
ubuntu_linux	eq	19.04
ubuntu_linux	eq	14.04
ubuntu_linux	eq	19.10
ubuntu_linux	eq	16.04
debian_linux	eq	9.0
debian_linux	eq	10.0
fedora	eq	30
fedora	eq	31
leap	eq	15.1