Affected: Homebrew: acronym

### Summary

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.

### Details

- **Vulnerability type:** File sandbox bypass - **Affected component:** `TransitionParser.train`, `TransitionParser.parse`, `AveragedPerceptron.save`, `AveragedPerceptron.load`, `PerceptronTagger.save_to_json`, `save_maxent_params` - **Affected versions:** Published `3.9.4` and current source `v3.10.0-rc2` both reproduced. - **Patched versions:** Not yet patched - **Root cause:** Model import and export helpers use built-in `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.

### PoC

**Preconditions** - The application enables `pathsec` enforcement and lets untrusted workflows choose model import or export paths.

**Steps** 1. Enable `pathsec.ENFORCE=True` and restrict allowed roots to a dedicated sandbox directory. 2. Use public model import or export APIs with paths that point outside that r…

NLTK through 3.10.3 contains a path traversal vulnerability in model-artifact APIs that bypass pathsec enforcement by using raw file operations on caller-controlled paths. Attackers can read or write files outside allowed sandbox roots through TransitionParser, AveragedPerceptron, PerceptronTagger, and maxent parameter APIs when pathsec is enabled.

Affected: PyPI: nltk

### Summary

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.

### Details

- **Vulnerability type:** File sandbox bypass - **Affected component:** `TransitionParser.train`, `TransitionParser.parse`, `AveragedPerceptron.save`, `AveragedPerceptron.load`, `PerceptronTagger.save_to_json`, `save_maxent_params` - **Affected versions:** Published `3.9.4` and current source `v3.10.0-rc2` both reproduced. - **Patched versions:** Not yet patched - **Root cause:** Model import and export helpers use built-in `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.

### PoC

**Preconditions** - The application enables `pathsec` enforcement and lets untrusted workflows choose model import or export paths.

**Steps** 1. Enable `pathsec.ENFORCE=True` and restrict allowed roots to a dedicated sandbox directory. 2. Use public model import or export APIs with paths that point outside that r…

Affected: PyPI: nltk

NLTK through 3.10.3 contains a path traversal vulnerability in model-artifact APIs that bypass pathsec enforcement by using raw file operations on caller-controlled paths. Attackers can read or write files outside allowed sandbox roots through TransitionParser, AveragedPerceptron, PerceptronTagger, and maxent parameter APIs when pathsec is enabled.

Affected: Ubuntu:Pro:14.04:LTS: nltk, Ubuntu:Pro:16.04:LTS: nltk, Ubuntu:Pro:18.04:LTS: nltk, Ubuntu:Pro:20.04:LTS: nltk, Ubuntu:Pro:22.04:LTS: nltk, Ubuntu:Pro:24.04:LTS: nltk, Ubuntu:Pro:26.04:LTS: nltk

NLTK through 3.10.3 contains a path traversal vulnerability in model-artifact APIs that bypass pathsec enforcement by using raw file operations on caller-controlled paths. Attackers can read or write files outside allowed sandbox roots through TransitionParser, AveragedPerceptron, PerceptronTagger, and maxent parameter APIs when pathsec is enabled.