HTCondor (daemon-to-daemon channel, negotiator/startd/schedd): Secret material crosses the network in the clear when

Impact

Secret material crosses the network in the clear when weak encryption is configured or when any 8.8-or-older daemon is still in the pool. An attacker who captures it can take over another user's slot and run code as that user, and can impersonate the negotiator and startd well enough to make the schedd hand over other users' jobs.

Who can reach it

Passive capture of HTCondor traffic between daemons - so anyone on the cluster network path, including a tenant on a compute node with a promiscuous interface or a compromised switch.

What to do

Upgrade to HTCondor 9.0.10 or 9.5.1, restart all daemons, and remove every pre-9.0 daemon from the pool - the mixed-version case is what reintroduces the cleartext path. Enable strong daemon-to-daemon encryption explicitly rather than relying on defaults.

References