Apache CXF before 3.3.4 and 3.2.11 does not restrict the number of message attachments present in a given message. This leaves open the possibility of a denial of service type attack, where a malicious user crafts a message containing a very large number of message attachments. From the 3.3.4 and 3.2.11 releases, a default limit of 50 message attachments is enforced. This is configurable via the message property "attachment-max-count".

Apache CXF has the ability to integrate with JMX by registering an InstrumentationManager extension with the CXF bus. If the createMBServerConnectorFactory property of the default InstrumentationManagerImpl is not disabled, then it is vulnerable to a man-in-the-middle (MITM) style attack. An attacker on the same host can connect to the registry and rebind the entry to another server, thus acting as a proxy to the original. They are then able to gain access to all of the information that is sent and received over JMX.

Apache CXF is vulnerable to cross-site scripting, caused by improper validation of user-supplied input by the services listing page. A remote attacker could exploit this vulnerability using a specially-crafted URL to execute script in a victim's Web browser within the security context of the hosting Web site, once the URL is clicked. An attacker could use this vulnerability to steal the victim's cookie-based authentication credentials.