CVE-2019-14870 Auth bypass in samba
Samba AD DC fails to enforce non-forwardable ticket restrictions for S4U2Self, allowing attackers to bypass delegation constraints and potentially escalate privileges.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2019-14870?
CVE-2019-14870 is a medium-severity authentication bypass vulnerability in Canonical Ubuntu Linux, published on 10 Dec 2019. Any signed-in user can exploit it over the network, with no action from the victim.
Official 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.
Which versions are affected by CVE-2019-14870?
It affects 5 products.
Products include Canonical Ubuntu Linux, Debian Debian Linux, Fedoraproject Fedora, Opensuse Leap, Samba Samba.
How do I fix CVE-2019-14870?
Upgrade to a fixed version.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2019-14870 being exploited?
There is no known exploitation of CVE-2019-14870 in the wild and no public exploit code.
Other vulnerabilities in Canonical Ubuntu Linux
Sources
Also known as ALPINE-CVE-2019-14870, CLEANSTART-2024-NY89465, DEBIAN-CVE-2019-14870, ECHO-6f51-4099-25c6, GHSA-6q5r-wx7g-rq28, UBUNTU-CVE-2019-14870.