GHSA-gx65-c5hj-vpv5

Duplicate Advisory

This advisory has been withdrawn because it is a duplicate of GHSA-rhp5-r9x4-f5g2. This link is maintained to preserve external references.

Original Description

NLTK before 3.10.0 (affected versions <=3.9.4) contains an unsafe pickle deserialization vulnerability in the TransitionParser.parse() method (nltk/parse/transitionparser.py). The method calls pickleload() with the default restricted=False, routing deserialization through WarningUnpickler, which does not override findclass() and therefore permits arbitrary class resolution. When an application loads an attacker-crafted model file, embedded pickle gadget chains execute arbitrary Python code with the privileges of the user running the application. NLTK provides a RestrictedUnpickler for safe deserialization, but it is not used by production code paths. Fixed in 3.10.0.