Resolved: A potential cross-site scripting exploit was found by Adam Roberts of NCC Group in one of the Keeper Desktop application popups related to the security certificate warning when connecting to a network proxy. The popup message on the Keeper Desktop application included information from the signed certificate to the user via the proxy. An iFrame in the certificate warning pulled information from the network proxy which could contain injected content.
Although Keeper's Content-Security-Policy disallows inline scripts from executing, Adam pointed out that an iFrame can open a local asset and potentially be a source of vulnerability. In order to exploit this, a user would need to first download a file to their local desktop and then connect to a network proxy which injected content via the certificate content. To prevent this from becoming a vulnerability, we now disallow iFrames via the Content-Security-Policy.
Special thanks to Adam Roberts of NCC Group for reporting this bug.