NLTK: URL-Encoded Path Traversal in nltk.data.load() Allows Arbitrary Local File Read

Summary

CVE	CVE-2026-54293
State	PUBLISHED
Assigner	GitHub_M
Source Priority	CVE Program / NVD first with legacy fallback
Published	2026-06-22 19:17:20 UTC
Updated	2026-06-30 03:21:02 UTC
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. Prior to 3.10.0-rc1, nltk.data.load() in NLTK is vulnerable to path traversal via URL-encoded path separators and traversal segments when using the nltk: URL scheme. The unsafe-path regex check is performed before url2pathname() decodes the %xx sequences (a classic decode-after-check / TOCTOU-style flaw), allowing an attacker to bypass the protection documented in NLTK's SECURITY.md and read arbitrary files from the filesystem. While literal traversal strings such as ../../../etc/passwd are correctly blocked, encoded variants such as %2fetc%2fpasswd, %2e%2e%2f..., and ..%2f..%2f slip past the regex and are subsequently decoded into a real filesystem path. This vulnerability is fixed in 3.10.0-rc1.

Risk And Classification

Primary CVSS: v3.1 7.5 HIGH from ADP

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

EPSS: 0.003780000 probability, percentile 0.298010000 (date 2026-07-04)

Problem Types: CWE-22 | CWE-22 CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') | CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Version	Source	Type	Score	Severity	Vector
3.1	ADP	CVSS	7.5	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`
3.1	[email protected]	Secondary	7.5	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`
3.1	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	Secondary	7.5	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`
3.1	CNA	DECLARED	7.5	HIGH	`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`

CVSS v3.1 Breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

None

Availability

None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N

NVD Known Affected Configurations (CPE 2.3)

Type	Vendor	Product	Version	Update	Edition	Language
Application	Nltk	Nltk	All	All	All	All

Vendor Declared Affected Products

Source	Vendor	Product	Version	Platforms
CNA	Nltk	Nltk	affected < 3.10.0-rc1	Not specified
ADP	Red Hat	Exploit Intelligence	Not specified	Not specified
ADP	Red Hat	OpenShift Lightspeed	Not specified	Not specified
ADP	Red Hat	Red Hat Ansible Automation Platform 2	Not specified	Not specified
ADP	Red Hat	Red Hat OpenShift AI RHOAI	Not specified	Not specified

References

Reference	Source	Link	Tags
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-54293.json	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	security.access.redhat.com
access.redhat.com/security/cve/CVE-2026-54293	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	access.redhat.com
github.com/nltk/nltk/security/advisories/GHSA-p4gq-832x-fm9v	134c704f-9b21-4f2e-91b3-4a467353bcc0	github.com	Exploit, Vendor Advisory
bugzilla.redhat.com/show_bug.cgi	0b0ca135-0b70-47e7-9f44-1890c2a1c46c	bugzilla.redhat.com
github.com/nltk/nltk/pull/3575	[email protected]	github.com	Issue Tracking, Patch
CVE Program record	CVE.ORG	www.cve.org	canonical
NVD vulnerability detail	NVD	nvd.nist.gov	canonical, analysis

No vendor comments have been submitted for this CVE.

Additional Advisory Data

Source	Time	Event
ADP	2026-06-22T19:01:09.319Z	Reported to Red Hat.
ADP	2026-06-22T17:25:05.611Z	Made public.

Workarounds

ADP: Update the nltk package to version 3.10.0 or later when a stable release is available. Upstream has fixed this issue in 3.10.0-rc1. Until updated builds are available, do not pass attacker-controlled resource identifiers to nltk.data.load() when using the nltk: URL scheme. Restrict NLTK data loading to trusted, application-controlled paths.

There are currently no legacy QID mappings associated with this CVE.