CVE-2026-64534
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk31th percentile - higher than 31% of all known CVEs
Summary
In the NVMe/TCP subsystem of the Linux kernel, in nvmet_tcp_try_recv_ddgst(), the call to nvmet_req_uninit() is unconditional. If the command arrived via the nvmet_tcp_handle_req_failure() path, the percpu_ref was never taken, leading to a refcount underflow and potential use-after-free.
Risk Assessment
A refcount underflow can lead to system crash, information disclosure, or potentially arbitrary code execution.
Recommendation
Apply the Linux kernel patch that checks the NVMET_TCP_F_INIT_FAILED flag before calling nvmet_req_uninit() in the digest error path.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: nvmet-tcp: check INIT_FAILED before nvmet_req_uninit in digest error path In nvmet_tcp_try_recv_ddgst(), when a data digest mismatch is detected, nvmet_req_uninit() is called unconditionally. However, if the command arrived via the nvmet_tcp_handle_req_failure() path, nvmet_req_init() had returned false and percpu_ref_tryget_live() was never executed. The unconditional percpu_ref_put() inside nvmet_req_uninit() then causes a refcount underflow, leading to a WARNING in percpu_ref_switch_to_atomic_rcu, a use-after-free diagnostic, and eventually a permanent workqueue deadlock. Check cmd->flags & NVMET_TCP_F_INIT_FAILED before calling nvmet_req_uninit(), matching the existing pattern in nvmet_tcp_execute_request().