OpenBao's Templated Policies Allow Privilege Escalation via Wildcard Characters

OpenBao is an open source identity-based secrets management system. Prior to 2.6.0, templated ACL, PKI, and SSH policies could substitute attacker-controlled identity data without rejecting syntax-significant characters. In ACL templated policies, asterisks, plus signs, and slashes could alter path matching. In PKI allowed_uri_sans_template and allowed_domains policies, an asterisk could broaden certificate issuance to unauthorized domains. In SSH allowed_users and allowed_domains policies, a comma could add unauthorized principals. Exploitation requires a deployment to use templated policy data that users can freely modify; templates based on the randomly generated identity.entity.id value are not affected. This could allow privilege escalation, unauthorized access, and unauthorized certificate issuance. This issue is fixed in version 2.6.0.