An issue was discovered in FusionAuth before 1.11.0. An authenticated user, allowed to edit e-mail templates (Home -> Settings -> Email Templates) or themes (Home -> Settings -> Themes), can execute commands on the underlying operating system by abusing freemarker.template.utility.Execute in the Apache FreeMarker engine that processes custom templates.

References

• https://nvd.nist.gov/vuln/detail/CVE-2020-7799
• https://fusionauth.io/docs/v1/tech/release-notes
• https://lab.mediaservice.net/advisory/2020-03-fusionauth.txt
• https://seclists.org/bugtraq/2020/Jan/39
• http://packetstormsecurity.com/files/156102/FusionAuth-1.10-Remote-Command-Execution.html