NLTK versions before 3.10.3 fail to use validated absolute paths when invoking the Graphviz dot binary in dependencygraph.dot2img and AlignedSent._repr_svg_, allowing attackers to execute arbitrary code by placing a malicious dot binary in the search path or current working directory. Attackers can exploit bare-name binary resolution on Windows via the current working directory or on Unix-like systems via relative PATH entries to execute their binary instead of the legitimate Graphviz tool.

NLTK versions before 3.10.3 contain a vulnerability in the dependencygraph.dot2img and AlignedSent._repr_svg_ functions that fail to use validated absolute paths when invoking the Graphviz dot binary. This allows attackers to execute arbitrary code by placing a malicious dot binary in the search path or current working directory. On Windows systems, attackers can exploit bare-name binary resolution via the current working directory, while on Unix-like systems they can abuse relative PATH entries. The vulnerability enables a classic binary hijacking/path traversal attack vector. Successful exploitation results in full arbitrary code execution with the privileges of the NLTK process. Users are advised to upgrade to NLTK version 3.10.3 or later to remediate the issue.