PYSEC-0000-CVE-2026-12252

In nltk/nltk versions 3.9.3 and earlier, five Stanford interface classes StanfordPOSTagger, StanfordNERTagger, StanfordParser, StanfordDependencyParser, and StanfordNeuralDependencyParser are vulnerable to untrusted JAR code execution. These classes accept user-controllable JAR paths and execute...

CVE-2026-12252

In nltk/nltk versions 3.9.3 and earlier, five Stanford interface classes StanfordPOSTagger, StanfordNERTagger, StanfordParser, StanfordDependencyParser, and StanfordNeuralDependencyParser are vulnerable to untrusted JAR code execution. These classes accept user-controllable JAR paths and execute...

Incomplete Fix for CVE-2026-0848: 5 Stanford Interface Classes Still Vulnerable to Untrusted JAR Code Execution

Description CVE-2026-0848 fixed untrusted JAR code execution in StanfordSegmenter by adding SHA256 verification in PR 3477. However, the fix was ONLY applied to nltk/tokenize/stanfordsegmenter.py. Five other Stanford interface classes have the identical vulnerability — they accept user-controllab...

Arbitrary Code Execution in NLTK StanfordSegmenter via untrusted JAR loading

Description nltk.tokenize.StanfordSegmenter dynamically loads external Java .jar files without verification or sandboxing. If an attacker can supply or replace the JAR e.g., a poisoned model download, MITM package swap, or dependency poisoning, arbitrary Java bytecode executes at import time...