Missing/wrong checks in lib/ext/pre_shared_key.c (server_recv_params)
In Line 489+ there is
while ((psk_index = _gnutls13_psk_ext_parser_next_psk(&psk_parser, &psk)) >= 0) {
...
It is possible that the loop terminates without some variables being set (resuming
and prf
). Within the loop not all possible conditions are covered.