This incident has been resolved.

We have identified the root cause as an issue generating random numbers from /dev/random and have deployed a fix. We are continuing to monitor the error rate from fetching SSH public keys.

We're once again seeing trouble with SSH fingerprint fetching in Pipelines, in which users who attempt to add a new remote SSH host will see an error "Unable to fetch fingerprints, check host SSH connection and try again". Our engineers are investigating now.