Is CVE-2026-67303 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-67303?

CVE-2026-67303 has a CVSS v3 severity of MEDIUM (4.3).

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CVE-2026-67303

Description

FreeRDP before 3.29.0 contains a reachable assertion (WINPR_ASSERT(OutputBufferLength == BytesReturned)) in serial_process_irp_device_control() in channels/serial/client/serial_main.c. When serial device redirection is enabled and a server-controlled IRP_MJ_DEVICE_CONTROL request specifies an unsupported IOCTL with a non-zero OutputBufferLength, CommDeviceIoControl() can fail with BytesReturned = 0, causing the mismatch to trigger the assertion and abort the client process (denial of service).