If you using IS-IS for MPLS, EXOS is not supported for md5 authentication but you could change configuration on cisco by using clear-text in key-chain instead md5.
for example, I assume you use "no switchport" in cisco for L3
Example
cisco(config)#key chain xxx
cisco(config-keychain)#key [number]
cisco(config-keychain-key)#key-string [text] <<< in these key-string you couldn't use mode 7 for hidden password.
After you setting key chain, you could enable isis authentication in yours interface by,
cisco(config)#interface XX0/x
cisco(config-int)isis authentication mode text
cisco(config-int)isis authentication key-chain xxx
---Done for Cisco---
from now, you go to EXOS and config IS-IS by,
X670#config isis vlan <vlan_name> password simple <same text as cisco key-string> level-1 ---Done for EXOS---
Let's try and report, pls.