NLTK up to 3.10.2 Corpus Readers open path traversal

Summaryinfo

A vulnerability, which was classified as problematic, has been found in NLTK up to 3.10.2. This affects the function Open of the component Corpus Readers. This manipulation causes path traversal. This vulnerability is registered as CVE-2026-79676. Remote exploitation of the attack is possible. No exploit is available.

Detailsinfo

A vulnerability has been found in NLTK up to 3.10.2 and classified as problematic. Affected by this vulnerability is the function open of the component Corpus Readers. 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. The summary by CVE is:

NLTK versions before 3.10.3 contain a path traversal vulnerability in corpus readers that reopen root-derived paths using built-in open() instead of nltk.pathsec.open(), allowing symlinks to escape trusted roots. Attackers who stage symlinked corpus files under a trusted data root can disclose outside-root content through normal corpus reader methods like channels(), domains(), and synonyms().

It is possible to read the advisory at github.com. This vulnerability is known as CVE-2026-79676 since 08/25/2026. The exploitation appears to be easy. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit. The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

Upgrading to version 3.10.3 eliminates this vulnerability.

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Productinfo

Name

• NLTK

Version

• 3.10.0
• 3.10.1
• 3.10.2

Website

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

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