I have done 2 rescans and i have not been able to reproduce this problem, so I think that nessus reported a false positive the first time the scan run.
Hi When doing a Nessus scan today i get a critical security vulnerability when scanning our only idrac 7 system on our network. Nessus says that the vulnerability is confirmed. If this is a real vulnerability a patch must be released asap. The idrac version is 1.57.57 Nessus plugin id: 77829
GNU Bash Environment Variable Handling Code Injection (Shellshock) idrac7 fw 
1.57.57