vulnerability / NVI-00010600 / Revision 1
NLTK: WekaClassifier passes an unvalidated caller-controlled model path to the weka JVM, bypassing nltk.pathsec containment
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.
This report has not inspected your inventory, configuration, deployed build, reachability or evidence. A catalog listing and a severity score do not establish exposure or compromise.
01 / Meaning
Why it matters
Published affected context helps an owner decide what evidence to gather. This report has not examined your application.
8.6 high
GitHub source severity; exploitability and local consequence require separate evidence.
As of · GitHub Advisory Database
02 / Applicability
The affected context
Affected versions, configuration prerequisites and known exclusions are public. Confirm each one against the deployed service.
nltk
source listed<= 3.10.3
## Summary `WekaClassifier` in NLTK passes a caller-controlled model file path to the weka Java VM without any `nltk.pathsec` validation. `WekaClassifier.train` puts the caller's `model_filename` verbatim into the weka argv `["-d", model_filename, ...]` (weka *writes* the trained model there), and `WekaClassifier._classify_many` puts `self._model` into `["-l", self._model, ...]` (weka *reads* it). Under `nltk.pathsec.ENFORCE=True` (the default on current HEAD), NLTK's stated invariant — established by advisory CVE-2026-81726 / GHSA-8mgp-746c-j5xp — is that caller-controlled model-artifact paths must be bounded to the allowed NLTK data roots before any native tool opens them. `WekaClassifier` is the one `java()`-based tool wrapper that skips this entirely, giving an untrusted workflow arbitrary-location file **write** (`-d`) and an arbitrary file **read/parse oracle** (`-l`), defeating pathsec containment. This is a standalone, unfixed variant of the same class as CVE-2026-81726, on a code path the CVE-2026-81726 fix never touched. That advisory enumerates 6 functions (`TransitionParser.train`, `TransitionParser.parse`, `AveragedPerceptron.save`, `AveragedPerceptron.load`, `Percept
03 / Response
What to do next
- investigate
Identify the exact component and deployed version, examine the linked publisher’s conditions, and retain evidence of any mitigation.
Confirm current vendor support, compatibility and deployment evidence. This report has not tested a fix in your system. GitHub Advisory Database
A fixed release is not deployment evidence.
Check current vendor support and compatibility. After making a change, verify the deployed build and relevant runtime conditions. Keep the evidence, owner and time. An updated lockfile alone does not prove what is running.
04 / Limits
What this report cannot establish
- Customer inventory, deployment, reachability and exploitation have not been inspected.
05 / Provenance
Sources you can inspect
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- GHSA-j456-xh4h-cpf2 ↗
GitHub Advisory Database · vendor advisory
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Public revision history
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- Revision 1 ·
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