is not possible in theory, because shadow files are not encrypted by passwords, but the hash,hash algorithm is irreversible, so there is no way to solve plaintext passwords from shadow, but there are some programs that can do "brute force cracking", that is, looking for matches from a large number of passwords that have already been hash. In this way, some weaker passwords can be cracked, but this is not a problem with the algorithm. There are some tools that can do this, but since cracking passwords is not something to encourage, it is not explained here.

cmd5.com
you can find some dictionaries to crack with John or hashcat. Dictionaries can consider living on their own or downloading some dictionaries