---
id: CVE-2026-78680
title: >-
  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
  …
summary: >-
  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
  …
severity: high
cvss: 7.8
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
cwe:
  - CWE-426
  - CWE-427
vendor: nltk
product: nltk
affected:
  - nltk < 3.10.3
patched:
  - nltk 3.10.3
published: '2026-08-25'
updated: '2026-10-12'
sourceUpdated: '2026-10-12T21:10:00.227'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-78680'
references:
  - url: 'https://github.com/nltk/nltk/security/advisories/GHSA-6hwm-xvph-95vm'
    label: disclosure@vulncheck.com
  - url: >-
      https://www.vulncheck.com/advisories/nltk-before-arbitrary-code-execution-via-graphviz-dot-binary
    label: disclosure@vulncheck.com
  - url: 'https://github.com/nltk/nltk/security/advisories/GHSA-6hwm-xvph-95vm'
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-78680'
  - url: >-
      https://github.com/nltk/nltk/commit/1a3cd1764ab3deb084fb66d0ffb4873717659538
  - url: 'https://github.com/nltk/nltk'
  - url: 'https://github.com/nltk/nltk/releases/tag/v3.10.3'
  - url: 'https://pypi.org/project/nltk'
  - url: 'https://github.com/advisories/GHSA-6hwm-xvph-95vm'
tags:
  - nvd
  - osv
  - pip
  - ghsa
epss: 0.00177
epssPercentile: 0.0719
aliases:
  - GHSA-6hwm-xvph-95vm
  - PYSEC-2026-3868
ecosystem: pip
ingestedAt: '2026-09-01T20:32:02.002Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-78680)

Affected packages:

- `nltk < 3.10.3`

Patched in:

- `nltk 3.10.3`

Source: https://osv.dev/vulnerability/GHSA-6hwm-xvph-95vm