PyPI · nltk
NLTK: Model-artifact APIs bypass pathsec and touch files outside allowed roots
Several model-artifact APIs still treat caller-controlled model paths as ordinary filenames even when NLTK path security is enforced. The same outside-root paths are rejected by guarded helpers, but these public read and write flows still use raw file APIs.
TransitionParser.train, TransitionParser.parse, AveragedPerceptron.save, AveragedPerceptron.load, PerceptronTagger.save_to_json, save_maxent_params3.9.4 and current source v3.10.0-rc2 both reproduced.open() on caller-controlled paths instead of pathsec-aware helpers.TransitionParser.train() writes outside allowed roots, TransitionParser.parse() reads outside allowed roots, AveragedPerceptron bypasses the sandbox in both directions, and adjacent read-side helpers in the same family already show the intended guarded behavior. I confirmed outside-root reads and writes while pathsec.open() or the guarded sibling helpers rejected the same paths.
Preconditions
pathsec enforcement and lets untrusted workflows choose model import or export paths.Steps
pathsec.ENFORCE=True and restrict allowed roots to a dedicated sandbox directory.pathsec.open(), PerceptronTagger.load_from_json(), or load_maxent_params().Minimal reproducible excerpt
transition_train_exists True
transition_parse_loader_read_bytes 13
averaged_load_keys ['bias']
maxent_save wrote ['alwayson.tab', 'labels.txt']
Consumers that rely on pathsec for local containment can be tricked into reading or overwriting files outside approved roots through normal model persistence and loading APIs.
Route all model-path file access through nltk.pathsec.open() or existing pathsec-aware helpers, and add regression tests that pair each vulnerable API with a negative control on the same path.
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Check my repoSources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.