A flaw was found in Spacewalk up to version 2.9 where it was vulnerable to XML internal entity attacks via the /rpc/api endpoint. An unauthenticated remote attacker could use this flaw to retrieve the content of certain files and trigger a denial of service, or in certain circumstances, execute arbitrary code on the Spacewalk server.
https://zeroauth.ltd/blog/2020/02/18/proof-of-concept-exploit-for-cve-2020-1693-spacewalk/
https://github.com/spacewalkproject/spacewalk/commit/74e28ec61d916c42061ef4347121650a1c962b0c