It's weird because when you read vulnerability (or at least when I say it) the first phoneme effectively becomes 'vun' - but in the abbreviated form one feels the need to mentally enunciate the 'l'.

I think the dropped l might just be your locale. I certainly pronounce it in the full word.

It's because vul-ner-a-bil-i-ty is being chopped in the middle of a syllable "ner",

"Vulner" is more pleasant than "vuln"

> oddly vulgar

My initial reaction was 'linguistically disgusting', but I decided to hold off the opinion, just in case I am strangely illiterate.

I've typed it, but I dunno if I've ever said it out loud. Kind of like i18n.

Same here. It is used internally here as a written abbreviation, and we use it as a prefix in a numbering scheme to identify a certain category of defects, but I don't think I've ever heard anyone use it verbally.