CVE-2026-64535

A use-after-free flaw was found in the Linux kernel's NVMe-over-Fabrics TCP target (nvmet-tcp) driver. When NVMe/TCP data digest is enabled and a digest mismatch occurs on a non-final H2C_DATA PDU during an R2T-based write transfer, the digest error handler in nvmet_tcp_try_recv_ddgst() calls nvmet_req_uninit(), which drops a percpu_ref reference on the submission queue without marking the command as completed. During the subsequent queue teardown, the same command is treated as still needing data and nvmet_req_uninit() is called a second time, resulting in a double percpu_ref_put against a single percpu_ref_get. This use-after-free and reference-count underflow can crash the kernel (denial of service) when a remote NVMe/TCP initiator triggers a digest mismatch against a host configured as an NVMe/TCP target.