NLTK up to 3.10.3 Model Artifact APIs path traversal

Summaryinfo

A vulnerability marked as critical has been reported in NLTK up to 3.10.3. This affects an unknown part of the component Model Artifact APIs. This manipulation causes path traversal. This vulnerability is handled as CVE-2026-81726. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability has been found in NLTK up to 3.10.3 and classified as critical. Affected by this vulnerability is an unknown code of the component Model Artifact APIs. The manipulation with an unknown input leads to a path traversal vulnerability. The CWE definition for the vulnerability is CWE-22. The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-81726 since 08/27/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/28/2026). The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

The vulnerability scanner Nessus provides a plugin with the ID 341153 (Linux Distros Unpatched Vulnerability : CVE-2026-81726), which helps to determine the existence of the flaw in a target environment.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

The vulnerability is also documented in the vulnerability database at Tenable (341153). Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

Productinfo

Name

• NLTK

Version

• 3.10.0
• 3.10.1
• 3.10.2
• 3.10.3

Website

• Product: https://github.com/nltk/nltk/

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Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.

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