When a CA's parent lives on the same Krill server: instead of building and verifying a signed CMS message, it runs the RFC 6492 provisioning exchange in-process and trusts the child identity (childhandle) that the caller put in the parent contact. Nothing checks that this child identity actually belongs to the CA making the request.

The vulnerability is that Krill encrypts every login-session token with a nonce built from a counter that is reset to 0 on every Krill restart, so the same (key, nonce) pair is used again after each restart.

NLnet Labs Krill supports direct access to the RRDP repository content through its built-in web server at the "/rrdp" endpoint. Prior to 0.12.1 a direct query for any existing directory under "/rrdp/", rather than an RRDP file such as "/rrdp/notification.xml" as would be expected, causes Krill to crash. If the built-in "/rrdp" endpoint is exposed directly to the internet, then malicious remote parties can cause the publication server to crash. The repository content is not affected by this, but the availability of the server and repository can cause issues if this attack is persistent and is not mitigated.