Linux Kernel SUNRPC Vulnerability in rpcb_register Functions

CVE-2026-89784

What is CVE-2026-89784?

A vulnerability exists in the Linux kernel related to the SUNRPC implementation, specifically within the rpcb_register_inet4 and rpcb_register_inet6 functions. The issue originates from insufficient checks on the return value of rpc_sockaddr2uaddr() before storing it in map->r_addr. If rpc_sockaddr2uaddr() returns NULL—indicating a kstrdup() failure—this unchecked NULL value can lead to a dereference issue during the encoding process in rpcb_register_call(). This can ultimately cause kernel crashes when an in-kernel RPC service registers under memory pressure, making it crucial to implement proper handling to prevent such occurrences.

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