Unbounded PPP IPCP Option Parsing Causes a Worker Stall and Out-of-bounds Read

In Eclipse ThreadX NetX Duo versions 6.0 through 6.5.2.202603a, the PPP IPCP code parses a peer's Configure-Nak without validating each option's length. A malicious PPP peer can stall the PPP thread indefinitely with a zero-length option, taking the link down, and can read back up to four bytes of packet-buffer memory per exchange with a short address option.