CVE-2026-33236
Description
A flaw was found in NLTK (Natural Language Toolkit), a suite of open-source Python modules for Natural Language Processing. The NLTK downloader does not validate subdir and id attributes when processing remote XML index files. A remote attacker can exploit this path traversal vulnerability by controlling a malicious XML index server, providing specially crafted values. This can lead to arbitrary directory creation, arbitrary file creation, and arbitrary file overwrite on the system where NLTK is used.
Statement
IMPORTANT: This flaw in NLTK allows for arbitrary file and directory creation or overwrite due to a path traversal vulnerability in its downloader. An attacker controlling a malicious XML index server could exploit this by providing specially crafted subdir and id attributes. Red Hat products utilizing NLTK, such as components within Red Hat Ansible Automation Platform, Lightspeed Core, OpenShift Lightspeed, and Red Hat OpenShift AI, are affected if configured to use untrusted remote XML index servers.
Mitigation
To mitigate this issue, ensure that any applications utilizing the NLTK downloader are configured to only interact with trusted XML index servers. Restrict network access for the application using NLTK to prevent connections to untrusted external resources. This operational control reduces the risk of an attacker controlling a malicious server to exploit the path traversal vulnerability. A service restart or reload may be required for network configuration changes to take effect.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8.1 | N/A | 8.1 |
| Attack Vector | Network | N/A | Network |
| Attack Complexity | Low | N/A | Low |
| Privileges Required | None | N/A | None |
| User Interaction | Required | N/A | Required |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | High | N/A | High |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
cve.org: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:H
Understanding the Weakness (CWE)
Integrity,Confidentiality,Availability
Technical Impact: Execute Unauthorized Code or Commands
The attacker may be able to create or overwrite critical files that are used to execute code, such as programs or libraries.
Integrity
Technical Impact: Modify Files or Directories
The attacker may be able to overwrite or create critical files, such as programs, libraries, or important data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, appending a new account at the end of a password file may allow an attacker to bypass authentication.
Confidentiality
Technical Impact: Read Files or Directories
The attacker may be able read the contents of unexpected files and expose sensitive data. If the targeted file is used for a security mechanism, then the attacker may be able to bypass that mechanism. For example, by reading a password file, the attacker could conduct brute force password guessing attacks in order to break into an account on the system.
Availability
Technical Impact: DoS: Crash, Exit, or Restart
The attacker may be able to overwrite, delete, or corrupt unexpected critical files such as programs, libraries, or important data. This may prevent the product from working at all and in the case of protection mechanisms such as authentication, it has the potential to lock out product users.
Frequently Asked Questions
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