CVE-2026-43825

/// Technical description

Untrusted Java Deserialization in Apache OpenNLP SvmDoccatModel

Versions Affected:

  before 3.0.0-M4 (libsvm document categorization module; introduced in

  OPENNLP-1808 and only present on the 3.x line)

Description:

SvmDoccatModel.deserialize(InputStream) reads an attacker-controlled

stream with java.io.ObjectInputStream and calls readObject() without an

ObjectInputFilter installed. ObjectInputStream materialises every class

referenced in the stream before the resulting object is cast to

SvmDoccatModel, so the cast that follows readObject() executes only

after the foreign object graph has already been deserialised in full.

If a Java deserialization gadget chain is available on the consumer's

classpath, a crafted payload supplied to

deserialize() executes arbitrary code in the JVM that loads it. Apache

OpenNLP itself does not ship a known gadget chain, so the realistic

risk is to downstream applications that embed the libsvm module

alongside vulnerable transitive dependencies. The m

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References