CVE-2026-64541

What is known

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix UAF in smc_cdc_rx_handler() by pinning the socket smc_cdc_rx_handler() looks up the connection by token under the link group's conns_lock, drops the lock, and then dereferences conn and the smc_sock derived from it, ending in sock_hold(&smc->sk) inside smc_cdc_msg_recv(). No reference is held across the lock release. The only reference pinning the socket while the connection is discoverable in the link group is taken in smc_lgr_register_conn() (sock_hold) and dropped in __smc_lgr_unregister_conn() (sock_put), both under conns_lock. Once the handler drops conns_lock, a concurrent close() -> smc_release() -> smc_conn_free() -> smc_lgr_unregister_conn() can drop that reference and free the smc_sock, so the handler's later sock_hold() runs on freed memory: WARNING: lib/refcount.c:25 at refcount_warn_saturate Workqueue: rxe_wq do_work refcount_warn_saturate (lib/refcount.c:25) smc_cdc_msg_recv (net/smc/smc_cdc.c:430) smc_cdc_rx_handler (net/smc/smc_cdc.c:502) smc_wr_rx_tasklet_fn (net/smc/smc_wr.c:445) tasklet_action_common (kernel/softirq.c:938) handle_softirqs (kernel/softirq.c:622) Kernel panic - not syncing: panic_on_warn set Only SMC-R is affected. The SMC-D receive tasklet is stopped by tasklet_kill(&conn->rx_tsklet) in smc_conn_free() before the connection is unregistered, so it cannot run concurrently with the free. Take the socket reference while still holding conns_lock, so the registration reference can no longer be the last one, and drop it once the handler is done.

Business impact

Successful exploitation of CVE-2026-64541, a reported vulnerability affecting the affected product, may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration.

Recommended administrator action

Confirm whether the affected product is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.

Sources

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