In affected Microsoft Windows versions of Octopus Deploy, the server can be coerced into sending server-side requests that contain authentication material allowing a suitably positioned attacker to compromise the account running Octopus Server and potentially the host infrastructure itself.
In affected versions of Octopus Server it was possible for a user with sufficient access to set custom headers in all server responses. By submitting a specifically crafted referrer header the user could ensure that all subsequent server responses would return 500 errors rendering the site mostly unusable. The user would be able to subsequently set and unset the referrer header to control the denial of service state with a valid CSRF token whilst new CSRF tokens could not be generated.
In affected versions of Octopus Deploy where customers are using Active Directory for authentication it was possible for an unauthenticated user to make an API request against two endpoints which would retrieve some data from the associated Active Directory. The requests when crafted correctly would return specific information from user profiles (Email address/UPN and Display name) from one endpoint and group information ( Group ID and Display name) from the other. This vulnerability does not expose data within the Octopus Server product itself.
In affected versions of Octopus Deploy it is possible for a low privileged guest user to craft a request that allows enumeration/recon of an environment.