there was an issue re cubeupload as some folk were using exe. files along with photos to push malware at one time. afaik this has been stopped by cubeupload and most if not all malware find engines were updated.
I dont use icubeupload myself, but mwb used to to red line it and not allow access to pics at one time.
Imagur is another freebie that works well. also flickr still, i think has a free low use policy too.

TBH tho i think the cost of most fee charging sites isnt prohibitive... Oh yes Tapatalk on mobiles is a good option too, although there will be ads soon if you dont pay £1 a month... Still not especially expensive and there is no minimum term..