NLTK has a Downloader Path Traversal Vulnerability (AFO) - Arbitrary File Overwrite
Priority HIGH 74CWE-22Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- Required
- Attack complexity
- Low
- Impact type
- —
- Confidentiality · integrity · availability
- None · High · High
- Fix status
- Partial Red Hat: 2 fixed, 4 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA, GitHub and Red Hat.
Summary
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.
Why it matters now
Exploitation Proof of concept CISA SSVC · not in CISA KEV
EPSS 0.00613 49th percentileScored 2026-11-07
Public exploit Yes 1 exploit referenceTagged by NVD
Fix Partial nltk (PyPI): 3.9.4Red Hat: 4 advisoriesRed Hat: 2 fixed, 4 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- Poc
- Automatable
- Yes
- Technical impact
- Partial
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| nltk | nltk | up to 3.9.3 | — | No fix listed | CNA |
| — | nltk (PyPI) | before 3.9.4 | 3.9.4 | Patch available | GHSA-469j-vmhf-r6v7 |
- nltk Vendornltk Affected up to 3.9.3 Fixed in — No fix listed CNA
- nltk (PyPI) Vendor— Affected before 3.9.4 Fixed in 3.9.4 Patch available GHSA-469j-vmhf-r6v7
Remediation
- Fix · GHSA-469j-vmhf-r6v7 nltk (PyPI) Fixed in 3.9.4 Advisory →
Red Hat 4 advisories
- RHSA-2026:42644 Released 2026-07-21 · Red Hat rating ImportantRHOAI 2.25.9 - Red Hat OpenShift AI
- Red Hat OpenShift AI 2.25 registry.redhat.io/rhoai/odh-caikit-tgis-serving-rhel9, registry.redhat.io/rhoai/odh-feature-server-rhel9, registry.redhat.io/rhoai/odh-kserve-storage-initializer-rhel9 +36
- RHSA-2026:37275 Released 2026-07-09 · Red Hat rating CriticalRHOAI 3.3.5 - Red Hat OpenShift AI
- Red Hat OpenShift AI 3.3 registry.redhat.io/rhoai/odh-dashboard-rhel9, registry.redhat.io/rhoai/odh-data-science-pipelines-operator-controller-rhel9, registry.redhat.io/rhoai/odh-feast-operator-rhel9 +45
- RHSA-2026:19712 Released 2026-05-20 · Red Hat rating CriticalRHOAI 3.3.3 - Red Hat OpenShift AI
- Red Hat OpenShift AI 3.3 registry.redhat.io/rhoai/odh-built-in-detector-rhel9, registry.redhat.io/rhoai/odh-dashboard-rhel9, registry.redhat.io/rhoai/odh-data-science-pipelines-argo-argoexec-rhel9 +33
Show 1 more Red Hat advisories
- RHSA-2026:10184 Released 2026-04-23 · Red Hat rating ImportantRHOAI 2.25.5 - Red Hat OpenShift AI
- Red Hat OpenShift AI 2.25 registry.redhat.io/rhoai/odh-caikit-nlp-rhel9, registry.redhat.io/rhoai/odh-caikit-tgis-serving-rhel9, registry.redhat.io/rhoai/odh-dashboard-rhel9 +47
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Lightspeed Core | Affected | No fix yet |
| OpenShift Lightspeed | Affected | No fix yet |
| Red Hat Ansible Automation Platform 2 | Affected | No fix yet |
| Red Hat OpenShift AI (RHOAI) | Affected | No fix yet |
| Red Hat OpenShift AI 2.25 | Fixed | RHSA-2026:10184, RHSA-2026:42644 |
| Red Hat OpenShift AI 3.3 | Fixed | RHSA-2026:19712, RHSA-2026:37275 |
Not affected: 3 products
- Red Hat Ansible Automation Platform 2
- Red Hat OpenShift AI 2.25
- Red Hat OpenShift AI 3.3
Timeline
- 2026-10-02 Threatist record created from CVE-2026-33236
- 2026-10-03 Alias added: GHSA-469j-vmhf-r6v7
- 2026-10-25 EPSS moved to the below the 50th percentile
- 2026-11-04 Fix available: PyPI/[email protected] · GHSA-469j-vmhf-r6v7
- 2026-11-04 8 new references · GHSA-469j-vmhf-r6v7
- 2026-11-06 Fix available: RHSA-2026:42644 · Red Hat
References
Other 9
- https://access.redhat.com/errata/RHSA-2026:10184
- https://access.redhat.com/errata/RHSA-2026:19712
- https://access.redhat.com/errata/RHSA-2026:37275
- https://access.redhat.com/errata/RHSA-2026:42644
- https://access.redhat.com/security/cve/CVE-2026-33236
- https://bugzilla.redhat.com/show_bug.cgi?id=2449824
- https://github.com/nltk/nltk
- https://github.com/pypa/advisory-database/tree/main/vulns/nltk/PYSEC-2026-2237.yaml
- https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-33236.json
More Nltk vulnerabilities
- TI-2026-00629 Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading CVSS 3.0CRITICAL 10.0
- TI-2025-12800 Zip Slip Vulnerability in nltk/nltk Leading to Remote Code Execution CVSS 3.0CRITICAL 10.0
- TI-2026-55173 NLTK before 3.10.3 JVM Argument Injection via Per-Call Options CVSS 4.0CRITICAL 9.3
- TI-2026-55155 NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization CVSS 4.0CRITICAL 9.3
- TI-2026-56370 nltk PorterStemmer before 3.10.3 Quadratic-time DoS CVSS 4.0HIGH 8.7
- TI-2026-55172 NLTK 3.10.2 Path Traversal via corpus-reader constructors CVSS 4.0HIGH 8.8
Sources
- CVE-2026-33236 · CVE Program
- CVE-2026-33236 · NVD
- FIRST EPSS
- GHSA-469j-vmhf-r6v7 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-33236 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences