CVE-2026-0846: NLTK arbitrary file read in nltk.util.filestring

CVE-2026-0846 · Severity: high · CVSS 8.6 · Published 2026-03-09

A vulnerability in the NLTK library, a popular tool for processing human language data, allows unauthorized access to files on a server. If an application using this library accepts user input without proper checks, an attacker could read sensitive system files or configuration data. This could lead to the exposure of private information or credentials, potentially compromising the entire system.

Technologies: NLTK Project Natural Language Toolkit, nltk (PyPI), Red Hat Ansible Automation Platform 2, Red Hat Lightspeed Core, Red Hat OpenShift Lightspeed. Vendors: NLTK Project, PyPI, Red Hat.

Quick answers

Is CVE-2026-0846 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-0846 being exploited in the wild.
How severe is CVE-2026-0846?
High severity, with a CVSS score of 8.6, published 9 March 2026.
Which products and versions are affected?
nltk (PyPI) < 3.9.3, ECOSYSTEM:introduced=0,fixed=3.9.3, ECOSYSTEM:introduced=0,last_affected=3.9.2; Red Hat Ansible Automation Platform 2 2.
Is there a fix for CVE-2026-0846?
Yes. nltk (PyPI): upgrade to 3.9.3 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-0846 attacked?
It is attacked over the network or with local access, in a software library.
Am I affected by CVE-2026-0846?
Check whether you run NLTK Project Natural Language Toolkit, nltk (PyPI), Red Hat Ansible Automation Platform 2 or one of the others listed at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • nltk (PyPI): upgrade to 3.9.3 or later
    pip install "nltk>=3.9.3"

Technical details

A path traversal vulnerability exists in the `filestring()` function of the `nltk.util` module in NLTK version 3.9.2. The root cause is improper validation of input paths, where the function directly opens files specified by user input without sanitization. An attacker can exploit this by providing absolute paths or traversal sequences (e.g., ../) to access sensitive system files. The vulnerability is reachable if the application exposes this function through a web API or any interface accepting user-supplied strings. Red Hat has issued security advisories (RHSA-2026:10184, RHSA-2026:19712) addressing this in their OpenShift AI and related products.

Affected products

  • nltk nltk 3.9.2
  • Red Hat Red Hat OpenShift AI 2.25, 3.3
  • Red Hat Red Hat Ansible Automation Platform 2 2
  • Red Hat Red Hat Lightspeed Core
  • Red Hat OpenShift Lightspeed

Identifiers

  • CVE-2026-0846
  • GHSA-h8wq-7xc4-p3qx
  • PYSEC-2026-97

Timeline

  • 2026-03-09: disclosed: Initial disclosure via huntr.dev
  • 2026-03-09: advisory: NVD published date
  • 2026-04-23: patched: Red Hat released security advisory RHSA-2026:10184
  • 2026-05-20: patched: Red Hat released security advisory RHSA-2026:19712

References

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