After my toot Cleo have issued a public advisory, they're saying versions up to 5.8.0.23 (not out yet) are impacted.
In terms of threat intel, the ransomware operators I know of only have an exploit for the Windows versions, not Linux.
https://support.cleo.com/hc/en-us/articles/28408134019735-Cleo-Product-Security-Advisory-CVE-Peding