CVE-2026-121953: FreeRDP before 3.32.2 has a use-after-free in the client's rdpgfx dynamic virtual channel: a duplicate-name channel with a new ChannelId overwrites the listener

FreeRDP before 3.32.2 has a use-after-free in the client's rdpgfx dynamic virtual channel: a duplicate-name channel with a new ChannelId overwrites the listener's single callback slot, which rdpgfx_on_close frees without clearing. A malicious RDP server can open and close such a channel, then send a PDU on the original channel to crash the client or potentially execute code.