Ask HN: Old Calcified libraries and APIs used in B2B apps

In another thread this statement was made.

>>>There are an amazing number of "business critical" applications that are running ancient libraries, protocols, etc.

Does anyone know of any examples of these "walking wounded" applications or libraries? Can we bring some attention to reduce their foot print?

Really big ones I can think of are SS7 telephone network protocol which has had a history of exploits against it and BGP where a misconfiguration at national level affect large parts of the internet.