Ubuntu: USN-2855-2: Samba regression

USN-2855-1 fixed vulnerabilities in Samba. The upstream fix for CVE-2015-5252introduced a regression in certain specific environments. This update fixes the problem.

Original advisory details:

Thilo Uttendorfer discovered that the Samba LDAP server incorrectly handled certain packets. A remote attacker could use this issue to cause the LDAP server to stop responding, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS, Ubuntu 15.04 and Ubuntu 15.10. (CVE-2015-3223) Jan Kasprzak discovered that Samba incorrectly handled certain symlinks. A remote attacker could use this issue to access files outside the exported share path. (CVE-2015-5252) Stefan Metzmacher discovered that Samba did not enforce signing when creating encrypted connections. If a remote attacker were able to perform a man-in-the-middle attack, this flaw could be exploited to view sensitive information. (CVE-2015-5296) It was discovered that Samba incorrectly performed access control when using the VFS shadow_copy2 module. A remote attacker could use this issue to access snapshots, contrary to intended permissions. (CVE-2015-5299) Douglas Bagnall discovered that Samba incorrectly handled certain string lengths. A remote attacker could use this issue to possibly access sensitive information. (CVE-2015-5330) It was discovered that the Samba LDAP server incorrectly handled certain packets. A remote attacker could use this issue to cause the LDAP server to stop responding, resulting in a denial of service. This issue only affected Ubuntu 14.04 LTS, Ubuntu 15.04 and Ubuntu 15.10. (CVE-2015-7540) Andrew Bartlett discovered that Samba incorrectly checked administrative privileges during creation of machine accounts. A remote attacker could possibly use this issue to bypass intended access restrictions in certain environments. This issue only affected Ubuntu 14.04 LTS, Ubuntu 15.04 and Ubuntu 15.10. (CVE-2015-8467)