Use-After-Free Vulnerability in Linux Kernel ksmbd Component

CVE-2026-89788

What is CVE-2026-89788?

A use-after-free vulnerability exists in the ksmbd component of the Linux kernel that can be exploited during the connection process. When the ksmbd_tree_conn_connect() function initializes a new tree connection and subsequently a concurrent session logoff occurs, it can erase the existing connection and free the referenced memory object. This race condition results in the handler attempting to access freed memory, potentially leading to unpredictable behavior or system crashes. Mitigating this issue involves implementing a proper reference count mechanism to ensure memory is safely managed and released only when all operations are complete. This change provides a more robust handling of connection states, reducing the risk of exploitation.

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