Is eating and drinking while standing considered among the major sins?

It is permissible to eat and drink while standing out of necessity, but it is disliked otherwise.

Anas ibn Malik was of the opinion that eating while standing is more disliked than drinking while standing.

The hadith of Ibn Umar indicates the permissibility of eating while walking and drinking while standing, and the majority of scholars interpret the hadiths prohibiting this as indicating a disliking of tanzih (disliked but not haram).