Serious Linux kernel security hole uncovered

Linux has issued an update to address a kernel-level security vulnerability that affected server message block (SMB) servers.

The remote code execution (RCE) flaw allowed unauthenticated users to execute kernel-level code and received the maximum possible severity rating on the common vulnerability reporting system (CVSS). Most businesses and enterprise users are believed to be safe from any potential exploitation given that the vulnerability only affected the lesser-used KSMBD module rather than the more popular Samba suite.

Specifically, the vulnerability lies in the processing of SMB2_TREE_DISCONNECT commands - packet requests sent by the client to request access to a given share on a server. “The issue results from the lack of validating the existence of an object prior to performing operations on the object,” read the public advisory posted by the Zero Day Initiative (ZDI). “An attacker can leverage this vulnerability to execute code in the context of the kernel.”