CVE-2026-33236

NLTK has a Downloader Path Traversal Vulnerability (AFO) - Arbitrary File Overwrite

At a glance

Severity: HIGH 8.1
EPSS: EPSS 0.60 % · percentile 48 (2026-10-27)
State: PUBLISHED
Published: 2026-03-20
Updated: 2026-07-21
Assigner: GitHub_M
NVD status: Modified

Description

NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Processing. In versions 3.9.3 and prior, the NLTK downloader does not validate the `subdir` and `id` attributes when processing remote XML index files. Attackers can control a remote XML index server to provide malicious values containing path traversal sequences (such as `../`), which can lead to arbitrary directory creation, arbitrary file creation, and arbitrary file overwrite. Commit 89fe2ec2c6bae6e2e7a46dad65cc34231976ed8a patches the issue.

Scores

Version	Score	Vector	Scored by
CVSS 3.1	HIGH 8.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H	GitHub_M
CVSS 3.1	HIGH 8.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H	redhat-SADP
CVSS 3.1	HIGH 8.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H	NVD · security-advisories@github.com (Secondary)
CVSS 3.1	HIGH 8.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H	NVD · 0b0ca135-0b70-47e7-9f44-1890c2a1c46c (Secondary)

Weaknesses (CWE)

CWE-22

Advisories

GHSA-469j-vmhf-r6v7 — NLTK has a Downloader Path Traversal Vulnerability (AFO) - Arbitrary File Overwrite
PYSEC-2026-2237 — NLTK (Natural Language Toolkit) is a suite of open source Python modules, data sets, and tutorials supporting research and development in Natural Language Proce

European references

ENISA EUVD · EUVD-2026-13887
GCVE · GCVE-0-2026-33236

CERT-FR advisories

CERTFR-2026-AVI-1378 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
CERTFR-2026-AVI-1206 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
CERTFR-2026-AVI-1094 — Multiples vulnérabilités dans les produits IBM · cert.ssi.gouv.fr
CERTFR-2026-AVI-0556 — Multiples vulnérabilités dans les produits VMware · cert.ssi.gouv.fr

Affected configurations (NVD CPE)

cpe:2.3:a:nltk:nltk:*:*:*:*:*:*:*:* ≤ 3.9.3

Affected products

Product	Versions
nltk · nltk	affected <= 3.9.3

References

Sources

Source	Licence
CVE List (CVEProject cvelistV5)	CVE Program Terms of Use
EPSS (FIRST.org)	FIRST — attribution requested
ENISA EUVD	ENISA — reproduction authorised, source acknowledged
CERT-FR (ANSSI)	Licence Ouverte / Etalab 2.0
NVD (NIST) via fkie-cad/nvd-json-data-feeds	Public domain — this product uses data from the NVD API but is not endorsed or certified by the NVD