Tibor Jager, Kenneth G. Paterson and Juraj Somorovsky have described XML encryption backwards compatibility attacks against various frameworks, including Apache CXF. An attacker can use these flaws to force a server to utilize insecure, legacy cryptosystems when secure cryptosystems are enabled on endpoints. This could expose flaws in the underlying legacy cryptosystems, such as CVE-2011-1096 and CVE-2011-2487. This flaw also affects the jbossws-native stack.

A flaw was found in JBoss web services where the services used a weak symmetric encryption protocol, PKCS#1 v1.5. An attacker could use this weakness in chosen-ciphertext attacks to recover the symmetric key and conduct further attacks.