CVE-2026-23376 in Linux
Summary
by MITRE • 03/25/2026
In the Linux kernel, the following vulnerability has been resolved:
nvmet-fcloop: Check remoteport port_state before calling done callback
In nvme_fc_handle_ls_rqst_work, the lsrsp->done callback is only set when remoteport->port_state is FC_OBJSTATE_ONLINE. Otherwise, the nvme_fc_xmt_ls_rsp's LLDD call to lport->ops->xmt_ls_rsp is expected to fail and the nvme-fc transport layer itself will directly call nvme_fc_xmt_ls_rsp_free instead of relying on LLDD's done callback to free the lsrsp resources.
Update the fcloop_t2h_xmt_ls_rsp routine to check remoteport->port_state. If online, then lsrsp->done callback will free the lsrsp. Else, return -ENODEV to signal the nvme-fc transport to handle freeing lsrsp.
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Analysis
by VulDB Data Team • 03/30/2026
The vulnerability CVE-2026-23376 resides within the Linux kernel's NVMe over Fabrics Fibre Channel loop transport implementation, specifically affecting the nvmet-fcloop subsystem. This issue represents a critical race condition and improper state management scenario that could lead to resource management failures and potential system instability. The vulnerability manifests when handling NVMe over Fibre Channel loop transport requests, where the transport layer fails to properly validate the remote port state before invoking completion callbacks, creating a scenario where memory management operations occur in incorrect states. The flaw directly impacts the nvme_fc_handle_ls_rqst_work function and the fcloop_t2h_xmt_ls_rsp routine, where improper state checking leads to inconsistent resource handling patterns.
The technical root cause of this vulnerability stems from inadequate state validation within the Fibre Channel loop transport layer's handling of NVMe over Fabre Channel logical requests. When the nvme_fc_handle_ls_rqst_work function processes logical service requests, it only sets the lsrsp->done callback when the remoteport->port_state equals FC_OBJSTATE_ONLINE. This conditional logic creates a scenario where the transport layer relies on different execution paths based on port state, but the fcloop_t2h_xmt_ls_rsp routine fails to perform the same state validation before proceeding with resource management operations. The missing state check means that when a remote port is not in the online state, the routine does not properly handle the resource cleanup path that should be triggered by the transport layer's direct call to nvme_fc_xmt_ls_rsp_free, instead potentially allowing the done callback to execute inappropriately or causing resource leaks.
The operational impact of this vulnerability extends beyond simple memory management issues to potentially affect system stability and data integrity within NVMe over Fibre Channel environments. When the transport layer incorrectly handles resource cleanup due to missing state validation, it can lead to memory leaks, double-free conditions, or improper resource deallocation that may cause system crashes or data corruption in storage environments. The vulnerability particularly affects systems utilizing NVMe over Fibre Channel loop transport mechanisms, where storage controllers and hosts communicate through Fibre Channel networks. The improper handling of port state transitions can result in inconsistent transport layer behavior, potentially allowing malicious actors to exploit timing conditions or force the system into unstable states during NVMe over Fibre Channel operations. This vulnerability aligns with CWE-362, which describes concurrent execution using shared data structures without proper synchronization, and could potentially map to ATT&CK technique T1059 for command injection or T1490 for data destruction if exploited in storage environments.
Mitigation strategies for CVE-2026-23376 require immediate kernel updates that implement the proper state validation within the fcloop_t2h_xmt_ls_rsp routine. The fix ensures that when remoteport->port_state is not FC_OBJSTATE_ONLINE, the routine returns -ENODEV to signal the transport layer to handle resource cleanup directly instead of relying on the done callback. System administrators should prioritize applying kernel patches that address this specific state management issue, particularly in production environments running NVMe over Fibre Channel storage configurations. Additionally, monitoring systems should be enhanced to detect anomalous port state transitions or resource management patterns that could indicate exploitation attempts. Organizations should implement comprehensive testing procedures to validate that the patched kernel correctly handles all port state transitions and resource cleanup scenarios, ensuring that the fix does not introduce regressions in normal operation. The vulnerability demonstrates the critical importance of proper state validation in kernel-level transport layer implementations and highlights the need for thorough testing of edge cases in storage protocol handling code.