vulnerability / NVI-00013904 / Revision 1
NLTK: Corpus readers follow symlinks outside trusted roots despite pathsec enforcement
GitHub lists this reviewed advisory for nltk. Published version ranges and source prerequisites are shown below; this is not an inspection of a visitor’s application.
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01 / Meaning
Why it matters
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02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
nltk
source listed<= 3.10.2
### Summary Several corpus readers still step outside NLTK's symlink-aware trusted-root model. They derive in-root paths from trusted corpus state, convert those paths back into plain strings, and reopen them with built-in `open()` rather than `nltk.pathsec.open()`. ### Details - **Vulnerability type:** Path traversal and symlink boundary bypass - **Affected component:** `nltk.corpus.reader.ipipan`, `nltk.corpus.reader.crubadan`, `nltk.corpus.reader.lin` - **Affected versions:** Published `3.9.4` and current source `v3.10.0-rc2` both reproduced. - **Patched versions:** Not yet patched - **Root cause:** Root-derived paths are reopened with raw `open()` without preserving the trusted-root boundary. `IPIPANCorpusReader` opens `header.xml` derived from `morph.xml`, `CrubadanCorpusReader` opens `table.txt` directly, and `LinThesaurusCorpusReader` opens `simN.lsp` paths returned from its own root helpers. Under `pathsec.ENFORCE=True`, a symlink placed inside the trusted corpus root can point outside the root and still be parsed successfully. It was confirmed parsed outside-root content is returned through public methods such as `channels()`, `domains()`, `categories()`, `langs()`, `c
03 / Response
What to do next
- investigate
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04 / Limits
What this report cannot establish
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05 / Provenance
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- GHSA-p4rw-rvv2-7xwr ↗
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- Revision 1 ·
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