Auth bypass in Samba
CVE-2019-14870
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.
Published · last modified .
CVSS v3 metric
CVSS v3 base score 5.4 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N.
EPSS exploit prediction
EPSS: 0.028 (85.8th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 86th percentile — 85.8% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.028 · newest: 0.028 · change: 0.000
Affected products
- Samba
- Canonical Ubuntu Linux — versions 14.04, 16.04, 18.04
- Debian Linux — versions 9.0, 10.0
- Fedoraproject Fedora — versions 30, 31
- openSUSE Leap — versions 15.1
- Red Hat Samba — versions all versions 4.11.x before 4.11.3, all versions 4.10.x before 4.10.11, all versions 4.x.x before 4.9.17
Weakness classification (CWE)
Public proof-of-concept exploits
References
- bugzilla.redhat.com/show_bug.cgi (Third Party Advisory, Issue Tracking)
- usn.ubuntu.com/4217-1/ (vendor-advisory, Third Party Advisory)
- security.netapp.com/advisory/ntap-20191210-0002/ (Third Party Advisory)
- www.samba.org/samba/security/CVE-2019-14870.html (Vendor Advisory)
- usn.ubuntu.com/4217-2/ (vendor-advisory, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- www.synology.com/security/advisory/Synology_SA_19_40 (Third Party Advisory)
- lists.opensuse.org/opensuse-security-announce/2019-12/msg00038.html (vendor-advisory, Mailing List, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- security.gentoo.org/glsa/202003-52 (vendor-advisory, Third Party Advisory)
Frequently asked questions
- What is CVE-2019-14870?
- CVE-2019-14870 is a medium-severity vulnerability in Samba, classified under Improper Authorization. CVSS score: 5.4/10. Published 2019-12-10.
- How severe is CVE-2019-14870?
- Medium severity. CVSS v3 base score is 5.4 out of 10.
- Is CVE-2019-14870 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.