CRITICAL

CVE-2026-79657

CVSS v3

9.8

CRITICAL

EPSS Score

1.3 %

exploit probability, as of 2026-10-19

CISA KEV

known exploited

Exploitation

—

SSVC status

Get an alert for each new CVE published for nltk.

Set up CVE WatchFree account · no credit card

Affected and fixed versions

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

nltkPyPIall versions · fixed in 3.10.3

Vendor advisories

CVE-2026-79657 Red Hat Product Security4 products fixed · 3 known affected
nltk: NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization
lightspeed-core/lightspeed-stack-rhel9 as a component of Lightspeed Core · openshift-lightspeed/lightspeed-ocp-rag-rhel9 as a component of OpenShift Lightspeed · ansible-automation-platform-25/lightspeed-chatbot-rhel8 as a component of Red Hat Ansible Automation Platform 2
RHSA-2026:84734 Red Hat Product Security4 products fixed
Red Hat Security Advisory: RHOAI 3.4.5 - Red Hat OpenShift AI

Full record on NVD

Description

NLTK versions before 3.10.3 contain a remote code execution vulnerability in allowlisted pickle loaders that trust entire module namespaces instead of specific safe callables. Attackers can craft malicious pickle payloads invoking dangerous in-namespace functions like ReppTokenizer._execute and numpy.f2py.crackfortran.myeval through pickle REDUCE to execute arbitrary commands during model or tokenizer artifact loading.

Technical details

CVSS v3 Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published: 2026-08-25
Last Modified: 2026-08-25

Frequently asked questions

What is CVE-2026-79657?

Is CVE-2026-79657 actively exploited?

Active exploitation of CVE-2026-79657 has not been confirmed. Its EPSS score was 1.3% on 2026-10-19, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-79657?

CVE-2026-79657 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

Running nltk? Hear about its next vulnerability

CVE Watch matches each new CVE to the vendors and products you list (vendor and product, not the version) and puts it in your alerts with its KEV and EPSS status.

Get alerts for this product CISA KEV additions, October 2026 Search CVEs

Already have an account? Open CVE WatchNo credit card required · No monthly cap on website lookups · 250 API requests/month

Go further

Following what attackers exploit right now? The CISA KEV additions of the month, with their patch deadlines.
Running this software? CVE Watch alerts you to new vulnerabilities in your products.

Related vulnerabilities

Same product first, then the same vendor advisory and the same publication week.

Back to CVE Database