Samba 4.9.3 Available for Download

Samba 4.9.3 (gzipped)

Patch (gzipped) against Samba 4.9.2

                   Release Notes for Samba 4.9.3
                         November 27, 2018

This is a security release in order to address the following defects:

o  CVE-2018-14629 (Unprivileged adding of CNAME record causing loop in AD
                   Internal DNS server)
o  CVE-2018-16841 (Double-free in Samba AD DC KDC with PKINIT)
o  CVE-2018-16851 (NULL pointer de-reference in Samba AD DC LDAP server)
o  CVE-2018-16852 (NULL pointer de-reference in Samba AD DC DNS servers)
o  CVE-2018-16853 (Samba AD DC S4U2Self crash in experimental MIT Kerberos
                   configuration (unsupported))
o  CVE-2018-16857 (Bad password count in AD DC not always effective)


o  CVE-2018-14629:
   All versions of Samba from 4.0.0 onwards are vulnerable to infinite
   query recursion caused by CNAME loops. Any dns record can be added via
   ldap by an unprivileged user using the ldbadd tool, so this is a
   security issue.

o  CVE-2018-16841:
   When configured to accept smart-card authentication, Samba's KDC will call
   talloc_free() twice on the same memory if the principal in a validly signed
   certificate does not match the principal in the AS-REQ.

   This is only possible after authentication with a trusted certificate.

   talloc is robust against further corruption from a double-free with
   talloc_free() and directly calls abort(), terminating the KDC process.

   There is no further vulnerability associated with this issue, merely a
   denial of service.

o  CVE-2018-16851:
   During the processing of an LDAP search before Samba's AD DC returns
   the LDAP entries to the client, the entries are cached in a single
   memory object with a maximum size of 256MB.  When this size is
   reached, the Samba process providing the LDAP service will follow the
   NULL pointer, terminating the process.

   There is no further vulnerability associated with this issue, merely a
   denial of service.

o  CVE-2018-16852:
   During the processing of an DNS zone in the DNS management DCE/RPC server,
   the internal DNS server or the Samba DLZ plugin for BIND9, if the
   property is set, the server will follow a NULL pointer and terminate.

   There is no further vulnerability associated with this issue, merely a
   denial of service.

o  CVE-2018-16853:
   A user in a Samba AD domain can crash the KDC when Samba is built in the
   non-default MIT Kerberos configuration.

   With this advisory we clarify that the MIT Kerberos build of the Samba
   AD DC is considered experimental.  Therefore the Samba Team will not
   issue security patches for this configuration.

o  CVE-2018-16857:
   AD DC Configurations watching for bad passwords (to restrict brute forcing
   of passwords) in a window of more than 3 minutes may not watch for bad
   passwords at all.

For more details and workarounds, please refer to the security advisories.

Changes since 4.9.2:

o  Andrew Bartlett <>
   * BUG 13628: CVE-2018-16841: heimdal: Fix segfault on PKINIT with
     mis-matching principal.
   * BUG 13678: CVE-2018-16853: build: The Samba AD DC, when build with MIT
     Kerberos is experimental

o  Tim Beale <>
   * BUG 13683: CVE-2018-16857: dsdb/util: Correctly treat
     lockOutObservationWindow as 64-bit int.

o  Joe Guo <>
   * BUG 13683: CVE-2018-16857 PEP8: Fix E305: Expected 2 blank lines after
     class or function definition, found 1.

o  Aaron Haslett <>
   * BUG 13600: CVE-2018-14629: dns: CNAME loop prevention using counter.

o  Gary Lockyer <>
   * BUG 13669: CVE-2018-16852: Fix NULL pointer de-reference in Samba AD DC
     DNS management.

o  Garming Sam <>
   * BUG 13674: CVE-2018-16851: ldap_server: Check ret before manipulating blob.