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Vulnerability PYSEC-2026-3867

High Risk

22 days ago

NLTK AllowlistUnpickler dotted-name validation bypass allows remote code execution

3.10.0 - 3.10.2

Summary

NLTK AllowlistUnpickler dotted-name validation bypass allows remote code execution

Details

NLTK before 3.10.3 contains a remote code execution vulnerability in AllowlistUnpickler that validates only the pickle module string and not the global name, allowing attackers to resolve dotted names by attribute traversal to callables outside the allowlisted namespace. Attackers can craft untrusted transition-parser models that execute arbitrary commands when TransitionParser.parse loads the model through allowlisted_pickle_load.

References

Related Vulnerabilities

Other vulnerabilities affecting the same packages

NLTK: Uncontrolled search path when invoking the Graphviz 'dot' binary

0.8 - 0.9.9 and 2.0b4 - 3.10.2 PYSEC-2026-3868

NLTK: Uncontrolled resource consumption in RecursiveDescentParser via ambiguous or left-recursive grammars

0.8 - 0.9.9 and 2.0b4 - 3.10.2 PYSEC-2026-3869

NLTK: Quadratic CPU Exhaustion in `XMLCorpusView._read_xml_fragment()`

0.8 - 0.9.9 and 2.0b4 - 3.10.2 PYSEC-2026-3871

NLTK TweetTokenizer vulnerable to denial of service through catastrophic regex backtracking

0.8 - 0.9.9 and 2.0b4 - 3.10.0 PYSEC-2026-3870

NLTK: Pl196xCorpusReader has quadratic ReDoS on malformed TEI blocks

0.8 - 0.9.9 and 2.0b4 - 3.10.2 GHSA-8mpw-7fpc-4gqj

View all vulnerabilities for these packages

Impacted packages

nltk

Timeline

Published

22 days ago

Fixed (3.10.3)

1 month ago

Last Modified

22 days ago