Ubuntu: (Multiple Advisories) (CVE-2021-3738): Samba regression

Description

Details for this vulnerability have not been published by NIST at this point. Descriptions from software vendor advisories for this issue are provided below.

From USN-5142-3:

USN-5142-1 fixed vulnerabilities in Samba. Some of the upstream changes introduced a regression in Kerberos authentication in certain environments.

Please see the following upstream bug for more information: https://bugzilla.samba.org/show_bug.cgi?id=14922

This update fixes the problem.

Original advisory details:

Stefan Metzmacher discovered that Samba incorrectly handled SMB1 client connections. A remote attacker could possibly use this issue to downgrade connections to plaintext authentication. (CVE-2016-2124)

Andrew Bartlett discovered that Samba incorrectly mapping domain users to local users. An authenticated attacker could possibly use this issue to become root on domain members. (CVE-2020-25717)

Andrew Bartlett discovered that Samba did not correctly sandbox Kerberos tickets issues by an RODC. An RODC could print administrator tickets, contrary to expectations. (CVE-2020-25718)

Andrew Bartlett discovered that Samba incorrectly handled Kerberos tickets. Delegated administrators could possibly use this issue to impersonate accounts, leading to total domain compromise. (CVE-2020-25719)

Andrew Bartlett discovered that Samba did not provide stable AD identifiers to Kerberos acceptors. (CVE-2020-25721)

Andrew Bartlett discovered that Samba did not properly check sensitive attributes. An authenticated attacker could possibly use this issue to escalate privileges. (CVE-2020-25722)

Stefan Metzmacher discovered that Samba incorrectly handled certain large DCE/RPC requests. A remote attacker could possibly use this issue to bypass signature requirements. (CVE-2021-23192)

William Ross discovered that Samba incorrectly handled memory. A remote attacker could use this issue to cause Samba to crash, resulting in a denial of service, or possibly escalate privileges. (CVE-2021-3738)

Joseph Sutton discovered that Samba incorrectly handled certain TGS requests. An authenticated attacker could possibly use this issue to cause Samba to crash, resulting in a denial of service. (CVE-2021-3671)

The fix forCVE-2020-25717results in possible behaviour changes that could affect certain environments. Please see the upstream advisory for more information:

https://www.samba.org/samba/security/CVE-2020-25717.html