This is PKCS#7 (well, CMS) encryption, not signing, the only places you're likely to find that is in S/MIME encrypted (not signed) email, and how often do you see that used? In theory other protocols that use CMS as a container format like SCEP could be affected, but that doesn't do AuthEnv. It also signs the encrypted data so the attacker would have to be the authorised/trusted party you're communicating with. There's also CMC, but that doesn't do AuthEnv either, although one of its infinite options does allow for unsigned encrypted data.