Samba 3.x and 4.x before 4.1.22, 4.2.x before 4.2.7, and 4.3.x before 4.3.3 supports connections that are encrypted but unsigned, which allows man-in-the-middle attackers to conduct encrypted-to-unencrypted downgrade attacks by modifying the client-server data stream, related to clidfs.c, libsmb_server.c, and smbXcli_base.c.
http://lists.fedoraproject.org/pipermail/package-announce/2015-December/174076.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-December/174391.html
http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00019.html
http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00020.html
http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00032.html
http://lists.opensuse.org/opensuse-security-announce/2015-12/msg00033.html
http://lists.opensuse.org/opensuse-security-announce/2016-01/msg00002.html
http://lists.opensuse.org/opensuse-security-announce/2016-01/msg00017.html
http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00042.html
http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00047.html
http://lists.opensuse.org/opensuse-security-announce/2016-04/msg00048.html
http://www.debian.org/security/2016/dsa-3433
http://www.oracle.com/technetwork/topics/security/bulletinjan2016-2867206.html
http://www.oracle.com/technetwork/topics/security/linuxbulletinjan2016-2867209.html
http://www.securityfocus.com/bid/79732
http://www.securitytracker.com/id/1034493
http://www.ubuntu.com/usn/USN-2855-1
http://www.ubuntu.com/usn/USN-2855-2
https://bugzilla.redhat.com/show_bug.cgi?id=1290292
https://git.samba.org/?p=samba.git;a=commit;h=1ba49b8f389eda3414b14410c7fbcb4041ca06b1
https://git.samba.org/?p=samba.git;a=commit;h=a819d2b440aafa3138d95ff6e8b824da885a70e9
https://git.samba.org/?p=samba.git;a=commit;h=d724f835acb9f4886c0001af32cd325dbbf1f895
https://h20566.www2.hpe.com/portal/site/hpsc/public/kb/docDisplay?docId=emr_na-c05115993
Source: MITRE
Published: 2015-12-29
Updated: 2018-10-30
Type: CWE-20
Base Score: 4.3
Vector: AV:N/AC:M/Au:N/C:N/I:P/A:N
Impact Score: 2.9
Exploitability Score: 8.6
Severity: MEDIUM
Base Score: 5.4
Vector: CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:N
Impact Score: 2.7
Exploitability Score: 2.2
Severity: MEDIUM