CVE-2026-0848

Name of the Vulnerable Software and Affected Versions NLTK versions prior to 3.9.3

Description Improper input validation in the StanfordSegmenter module allows for arbitrary code execution. The module dynamically loads external Java .jar files without verification or sandboxing, enabling an attacker to supply or replace a JAR file to execute arbitrary Java bytecode during import. This can be achieved through model poisoning, Man-in-the-Middle (MitM) attacks, or dependency poisoning. The issue stems from the direct execution of the JAR file via a subprocess using unvalidated classpath input, which allows malicious classes to run when loaded by the Java Virtual Machine (JVM).

Recommendations Update to a version newer than 3.9.2. As a temporary workaround, restrict the use of the StanfordSegmenter module to minimize the risk of exploitation.