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 <clinit> of SomeClass — and many real-world classes have side-effecting static initialisers
Both issues have been fixed.
CVSS Details
- CVSS 3.1 Base Score: 9.8
- CVSS 3.1 Vector: (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H)
Covered by Rapid7
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Redhat_linux | — | — | Jul 31, 2026 | Jun 3, 2026 |
| Ubuntu | — | Upgrade libmina2-java (Ubuntu Pro) | Jun 24, 2026 | Jun 23, 2026 |
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