ZDRES-232: resolveProxyClass Not Overridden – acceptMatchers Filter Bypass via java.lang.reflect.Proxy
Assessment: Fully addressed.
When the serialised stream contains a TC_PROXYCLASSDESC (the marker
for a java.lang.reflect.Proxy ), JDK’s ObjectInputStream.readProxyDesc()
is
dispatched. JDK then calls the default
ObjectInputStream.resolveProxyClass(interfaces) implementation, which
performs Class.forName(intf, false, latestUserDefinedLoader()) for EACH
interface name and constructs the proxy class — bypassing the accepted
classes list .
ZDRES-233: Class.forName(name, initialize=true, classLoader) in
readClassDescriptor Triggers Static Initialiser of Allow-Listed Classes
Assessment: Fully addressed.
For ANY class on the allow-list, deserialising a stream that names it triggers the class’s
(static initialiser) BEFORE any instance is constructed. This means an
attacker who supplies a class name on the allow-list (e.g., the
developer wrote accept(“com.myapp.*”) , attacker supplies
com.myapp.SomeClass ) causes of SomeClass — and many
real-world classes have side-effecting static initialisers
Both issues have been fixed.
