Opencast users with ROLE_COURSE_ADMIN can create new users

Vulnerability Description

In Opencast before 7.6 and 8.1, users with the role ROLE_COURSE_ADMIN can use the user-utils endpoint to create new users not including the role ROLE_ADMIN. ROLE_COURSE_ADMIN is a non-standard role in Opencast which is referenced neither in the documentation nor in any code (except for tests) but only in the security configuration. From the name – implying an admin for a specific course – users would never expect that this role allows user creation. This issue is fixed in 7.6 and 8.1 which both ship a new default security configuration.

References

• https://github.com/opencast/opencast/security/advisories/GHSA-94qw-r73x-j7hg
• https://github.com/opencast/opencast/commit/72fad0031d8a82c860e2bde0b27570c5042320ee