CVE-2026-128134 · Package
NO FIX YET · SEE WHAT TO DO
NLTK's dependency graph renderer finds the Graphviz dot program through the PATH variable and runs it without its trusted-executable checks. A local user who can write to a PATH directory on a POSIX system can plant a fake dot program that runs as the victim when dot2img or DependencyGraph.repr_svg is called.
first public Oct 26, 2026 · 1 source
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Only POSIX systems where NLTK's dependency graph code (dot2img or DependencyGraph.repr_svg) runs and where a low-privileged local user can write to a PATH directory. The sources say the current-directory bare-name case is a separate, already blocked issue. Environments with no writable PATH entries and no local untrusted users are lower risk.
Not affected if nltk-3.10.4-or-later, no-graphviz-rendering, no-untrusted-local-users
Who cares graphviz, nltk, posix, python
python -c "import nltk; print(nltk.__version__)", and treat any version below 3.10.4 as affected.echo $PATH and ls -ld on each entry.3.10.4.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.
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