nltk: NLTK before 3.10.0 (affected versions <=3.9.4) contains an unsafe pickle deserialization vulnerability in the Transit...
CVE-2026-78683 is fixed in nltk on 1 platform by DEBIAN-CVE-2026-78683 (version 3.10.0-1), released August 26, 2026. It is not reported as exploited. Patch Radar priority: Routine.
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 pickle_load() with the default restricted=False, routing deserialization through WarningUnpickler, which does not override find_class() 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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| nltk · Debian 14 | 3.10.0-1 | DEBIAN-CVE-2026-78683 | Aug 26, 2026 |
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