Ubuntu Security Notice 2950-5 – USN-2950-1 fixed vulnerabilities in Samba. USN-2950-3 updated Samba to version 4.3.9, which introduced a regression when using the ntlm_auth tool. This update fixes the problem. Jouni Knuutinen discovered that Samba contained multiple flaws in the DCE/RPC implementation. A remote attacker could use this issue to perform a denial of service, downgrade secure connections by performing a man in the middle attack, or possibly execute arbitrary code. Stefan Metzmacher discovered that Samba contained multiple flaws in the NTLMSSP authentication implementation. A remote attacker could use this issue to downgrade connections to plain text by performing a man in the middle attack. Alberto Solino discovered that a Samba domain controller would establish a secure connection to a server with a spoofed computer name. A remote attacker could use this issue to obtain sensitive information. Various other issues were also addressed.