A memory exhaustion issue was found in ksmbd, a high-performance in-kernel SMB server. Quoting ZDI security advisory [1]:

"This vulnerability allows remote attackers to create a denial-of-service condition on affected installations of Linux Kernel. Authentication is not required to exploit this vulnerability, but only systems with ksmbd enabled are vulnerable.

The specific flaw exists within the handling of SMB2_SESSION_SETUP commands. The issue results from the lack of control of resource consumption. An attacker can leverage this vulnerability to create a denial-of-service condition on the system."

[1] https://www.zerodayinitiative.com/advisories/ZDI-CAN-20478/