There are 2 open security issues in bullseye.
1 important issue:
Attackers can create long chains of CAs that would lead to OctoRPKI exceeding its max iterations parameter. In consequence it would cause the program to crash, preventing it from finishing the validation and leading to a denial of service.
1 issue left for the package maintainer to handle:
(postponed; to be fixed through a stable update)
NLnet Labs Routinator prior to 0.10.2 happily processes a chain of RRDP repositories of infinite length causing it to never finish a validation run. In RPKI, a CA can choose the RRDP repository it wishes to publish its data in. By continuously generating a new child CA that only consists of another CA using a different RRDP repository, a malicious CA can create a chain of CAs of de-facto infinite length. Routinator prior to version 0.10.2 did not contain a limit on the length of such a chain and will therefore continue to process this chain forever. As a result, the validation run will never finish, leading to Routinator continuing to serve the old data set or, if in the initial validation run directly after starting, never serve any data at all.
You can find information about how to handle this issue in the security team's documentation.