Isode M-Link before 16.0v7 does not properly restrict the processing of compressed XML elements, which allows remote attackers to cause a denial of service (resource consumption) via a crafted XMPP stream, aka an "xmppbomb" attack.

M-Link R14.6 before R14.6v14 and R15.1 before R15.1v10 does not verify that a request was made for an XMPP Server Dialback response, which allows remote XMPP servers to spoof domains via responses for domains that were not asserted.

M-Link Archive Server in Isode M-Link R16.2v1 through R17.0 before R17.0v24 allows non-administrative users to access and manipulate archive data via certain HTTP endpoints, aka LINK-2867.