6.8 - DSA-3740

Several vulnerabilities have been discovered in Samba, a SMB/CIFS file, print, and login server for Unix. The Common Vulnerabilities and Exposures project identifies the following issues:

CVE-2016-2119

Stefan Metzmacher discovered that client-side SMB2/3 required signing can be downgraded, allowing a man-in-the-middle attacker to impersonate a server being connected to by Samba, and return malicious results.

CVE-2016-2123

Trend Micro's Zero Day Initiative and Frederic Besler discovered that the routine ndr_pull_dnsp_name, used to parse data from the Samba Active Directory ldb database, contains an integer overflow flaw, leading to an attacker-controlled memory overwrite. An authenticated user can take advantage of this flaw for remote privilege escalation.

CVE-2016-2125

Simo Sorce of Red Hat discovered that the Samba client code always requests a forwardable ticket when using Kerberos authentication. A target server, which must be in the current or trusted domain/realm, is given a valid general purpose Kerberos "Ticket Granting Ticket" (TGT), which can be used to fully impersonate the authenticated user or service.

CVE-2016-2126

Volker Lendecke discovered several flaws in the Kerberos PAC validation. A remote, authenticated, attacker can cause the winbindd process to crash using a legitimate Kerberos ticket due to incorrect handling of the PAC checksum. A local service with access to the winbindd privileged pipe can cause winbindd to cache elevated access permissions.

For the stable distribution (jessie), these problems have been fixed in version 2:4.2.14+dfsg-0+deb8u2. In addition, this update contains several changes originally targeted for the upcoming jessie point release.

We recommend that you upgrade your samba packages.