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.
Source: samba (LP Ubuntu Debian)
Upstream:released (4.11.3,4.10.11,4.9.17)
Ubuntu 12.04 ESM (Precise Pangolin):needs-triage
Ubuntu 14.04 ESM (Trusty Tahr):released (2:4.3.11+dfsg-0ubuntu0.14.04.20+esm4)
Ubuntu 16.04 LTS (Xenial Xerus):released (2:4.3.11+dfsg-0ubuntu0.16.04.24)
Ubuntu 18.04 LTS (Bionic Beaver):released (2:4.7.6+dfsg~ubuntu-0ubuntu2.14)
Ubuntu 19.04 (Disco Dingo):released (2:4.10.0+dfsg-0ubuntu2.7)
Ubuntu 19.10 (Eoan Ermine):released (2:4.10.7+dfsg-0ubuntu2.3)
Ubuntu 20.04 (Focal Fossa):needed
More Information

Updated: 2019-12-11 17:14:25 UTC (commit 714b17c8ba8c1aeb6a1ebaee6d37eed1bc3c845c)