CVE-2026-41586

Ein Angreifer kann mehrere Schwachstellen in IBM DB2 ausnutzen, um beliebigen Programmcode auszuführen, beliebige Dateien zu schreiben, Daten zu manipulieren, sensible Informationen offenzulegen oder Denial-of-Service-Zustände zu verursachen.

## Summary This advisory covers the deprecated `fabric-sdk-java` client SDK. `Channel.java` implements `readObject()` and exposes `deSerializeChannel()` which call `ObjectInputStream.readObject()` on untrusted byte arrays without configuring an `ObjectInputFilter`. This is the classic Java deserialization RCE pattern. **Note:** `fabric-sdk-java` is deprecated and maintained in https://github.com/hyperledger/fabric-sdk-java. Filing here as that repo does not have private vulnerability reporting enabled. ## Affected Code ```java // src/main/java/org/hyperledger/fabric/sdk/Channel.java private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException { in.defaultReadObject(); // No ObjectInputFilter configured } public Channel deSerializeChannel(byte[] channelBytes) throws IOException, ClassNotFoundException, InvalidArgumentException { ObjectInputStream ois = new ObjectInputStream(new ByteArrayInputStream(channelBytes)); Channel channel = (Channel) ois.readObject(); // Untrusted bytes deserialized return channel; } ``` ## Attack Vector An attacker who can supply crafted serialized Channel bytes to the client application — for example, by compromising a local channel file, injecting data through an application that accepts Channel bytes from external sources, or exploiting a separate write primitive — can achieve RCE via gadget chain exploitation when deSerializeChannel() processes those bytes. The risk is highest in deployments that accept Channel data from sources outside the client's direct control. Note: channel data is not transmitted from Fabric peers; this is a client-side deserialization surface. ## Proof of Concept ```java // Generate malicious payload with ysoserial: // java -jar ysoserial.jar CommonsCollections6 "touch /tmp/pwned" > malicious_channel.ser // Victim code: byte[] maliciousBytes = Files.readAllBytes(Paths.get("malicious_channel.ser")); Channel channel = client.deSerializeChannel(maliciousBytes); // RCE fires here ``` ## Notes on Deprecation fabric-sdk-java is deprecated as of Hyperledger Fabric v2.5 (replaced by `org.hyperledger.fabric:fabric-gateway`). However, organizations that have not yet migrated remain fully exposed. Automated dependency scanners (Snyk, Dependabot) cannot alert users without a published GHSA. This advisory is filed to ensure those users are notified and directed to migrate. ## Fix For the deprecated SDK: add `ObjectInputFilter` to whitelist only expected classes: ```java ObjectInputFilter filter = ObjectInputFilter.Config.createFilter( "org.hyperledger.fabric.sdk.*;java.util.*;java.lang.*;!*" ); ois.setObjectInputFilter(filter); ``` **The recommended remediation is migration to `org.hyperledger.fabric:fabric-gateway`**, which does not use Java serialization. ## Resources - CWE-502: Deserialization of Untrusted Data - Migration guide: https://hyperledger.github.io/fabric-gateway/ ## Credits Found by [Martin Brodeur (brodmart)](https://github.com/brodmart) via independent security research.

Hyperledger Fabric is an enterprise-grade permissioned distributed ledger framework for developing solutions and applications. From versions 1.0.0 to 2.2.26, Channel.java implements readObject() and exposes deSerializeChannel() which call ObjectInputStream.readObject() on untrusted byte arrays without configuring an ObjectInputFilter. This is a classic Java deserialization RCE pattern. At time of publication, there are no publicly available patches.

Hyperledger Fabric is an enterprise-grade permissioned distributed ledger framework for developing solutions and applications. From versions 1.0.0 to 2.2.26, Channel.java implements readObject() and exposes deSerializeChannel() which call ObjectInputStream.readObject() on untrusted byte arrays without configuring an ObjectInputFilter. This is a classic Java deserialization RCE pattern. At time of publication, there are no publicly available patches.

Hyperledger Fabric is an enterprise-grade permissioned distributed ledger framework for developing solutions and applications. From versions 1.0.0 to 2.2.26, Channel.java implements readObject() and exposes deSerializeChannel() which call ObjectInputStream.readObject() on untrusted byte arrays without configuring an ObjectInputFilter. This is a classic Java deserialization RCE pattern. At time of publication, there are no publicly available patches.