Summary

When a crafted ed25519 private key is loaded which contains an insane number of rounds, it will lock net/ssh in an infinite CPU-time consuming loop for a very long time trying to load the key. That the key itself is not a real ssh key does not matter in this regard.

Impact

The resulting ruby process will hang for several days (estimated at least half a year) and be locked in the C call, needing to manually terminate the corresponding ruby process.