NLTK up to 3.10.3 DependencyGraph dependencygraph.py nltk.parse.dependencygraph.dot2img path traversal

Summaryinfo

A vulnerability categorized as problematic has been discovered in NLTK up to 3.10.3. This affects the function nltk.parse.dependencygraph.dot2img of the file nltk/parse/dependencygraph.py of the component DependencyGraph. Executing a manipulation can lead to path traversal. This vulnerability appears as CVE-2026-128134. The attack requires local access. There is no available exploit. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability has been found in NLTK up to 3.10.3 and classified as problematic. This vulnerability affects the function nltk.parse.dependencygraph.dot2img of the file nltk/parse/dependencygraph.py of the component DependencyGraph. 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. CVE summarizes:

NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. Prior to 3.10.4, nltk.parse.dependencygraph.dot2img resolves the Graphviz dot executable through PATH but invokes the resulting absolute executable without routing through spawn_trusted, so resolve_trusted_executable ownership and writability validation and safe_env loader environment scrubbing do not run. A local low-privileged attacker who can write to a directory on a POSIX victim's PATH can plant or replace dot, and code executes as the victim when dot2img is called directly or DependencyGraph.repr_svg renders a graph. The current-working-directory-only bare-name vector is blocked and is not this vulnerability; this issue is the residual writable absolute PATH element bypass after CVE-2026-78680. This issue is fixed in version 3.10.4.

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-128134 since 11/12/2026. The exploitation appears to be easy. The attack needs to be approached locally. Successful exploitation requires user interaction by the victim. There are known technical details, but no exploit is available. The MITRE ATT&CK project declares the attack technique as T1006.

Upgrading to version 3.10.4 eliminates this vulnerability.

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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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