Dead.Letter (CVE-2026-45185): XBOW가 Exim에서 인증되지 않은 RCE를 발견한 방법

int tls_ungetc(int ch) {
  if (ssl_xfer_buffer_lwm < ssl_xfer_buffer_hwm)
    return state_server.xfer_buffer[--state_server.xfer_buffer_lwm] = ch;
  return EOF;
}

static inline void bdat_push_receive_functions(void) {
  if (!lwr_receive_getc) {
    lwr_receive_getc = receive_getc;
    lwr_receive_getbuf = receive_getbuf;
    lwr_receive_hasc = receive_hasc;
    lwr_receive_ungetc = receive_ungetc;
  }
  receive_getc = bdat_getc;
  receive_getbuf = bdat_getbuf;
  receive_hasc = bdat_hasc;
  receive_ungetc = bdat_ungetc;
}