NVD / CVE Program· CNA GitHub_M

CVE-2026-54293: NLTK: URL-Encoded Path Traversal in nltk.data.load() Allows Arbitrary Local File Read

Noroxi assessment

Priority: Monitor (action score 30/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 0.63% (FIRST EPSS); higher than 50.1% of all records.
Anyone who can reach it over the internet can trigger it. No account or password is required. No user action is required. No special conditions are required; it is repeatable.
According to CISA the attack is automatable: targets can be found by mass scanning.
Fixed version: nltk nltk 3.10.0-rc1.

Low priority for now. Upgrade to nltk nltk 3.10.0-rc1 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

HighCVSS 7.5 · v3.1—No exploit Fix available

Published: Jun 22, 2026
Updated: Sep 9, 2026
EPSS: 0.6% · 50th percentile
CWE: CWE-22

Report tools

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Action score

Monitor

Low priority for now.

CVSS: 30 / 40 · 7.5 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.6%

CISA SSVC decision

Exploitation: proof of concept
Automatable: yes
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · GitHub_M: 7.5; NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

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Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

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Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

Vendor	Product	CPE
nltk	nltk	cpe:2.3:a:nltk:nltk

Affected versions

NVD version ranges (for catalog products). Add the product to your stack with a version and matching uses these.

nltk nltkbefore 3.10.0

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitHub_M). Independent of NVD's CPE analysis and usually ahead of it.

nltk nltk
- < 3.10.0-rc1affected

Package-level exposure

OSV and GitHub Advisory data: ecosystem, package and range. SBOM matching uses this table.

Ecosystem	Package	Affected range	Fix
Debian:12	nltk	from 0	—
Debian:14	nltk	before 3.10.0-1	3.10.0-1
openSUSE:Tumbleweed	python-nltk	before 3.10.0rc1-1.1	3.10.0rc1-1.1
PyPI	nltk	before 3.10.0	3.10.0

Same product

nltk: all records

Other highest-scoring records for the same primary product.

CVE-2026-0848Arbitrary Code Execution in NLTK StanfordSegmenter via Untrusted JAR Loading
40Plan
CVE-2026-79675NLTK before 3.10.3 JVM Argument Injection via Per-Call Options
37Monitor
CVE-2026-79657NLTK before 3.10.3 Remote Code Execution via Unsafe Pickle Deserialization
37Monitor

Published before and after this one in the same product

← EarlierCVE-2026-33231Mar 20, 2026 · NLTK has unauthenticated remote shutdown in nltk.app.wordnet_app
30Monitor
← EarlierCVE-2026-33236Mar 20, 2026 · NLTK has a Downloader Path Traversal Vulnerability (AFO) - Arbitrary File Overwrite
32Monitor
Later →CVE-2026-12252Jul 4, 2026 · Untrusted JAR Code Execution in Multiple Stanford Interface Classes in nltk/nltk
31Monitor

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / package	Fixed version	Source
nltk nltk	3.10.0-rc1 · description	Vendor (CNA)
debian:nltk	3.10.0-1 · Debian:14	Package registry (OSV)
opensuse:python-nltk	3.10.0rc1-1.1 · openSUSE:Tumbleweed	Package registry (OSV)
PyPI:nltk	3.10.0	Package registry (OSV)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

nltk/nltkPR 3575

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

No credits in the CNA record.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

CVE-2026-6238461 days apartNLTK FramenetCorpusReader Symlink Sandbox Bypass before 3.10.2
34Monitor
CVE-2026-6331261 days apartNLTK StreamBackedCorpusView Bypasses pathsec.ENFORCE Arbitrary File Read
34Monitor
CVE-2026-109956113 days apartNLTK through 3.10.3 Path Traversal via WekaClassifier Model Path
33Monitor
CVE-2026-7967664 days apartNLTK before 3.10.3 Path Traversal via Symlink Bypass
32Monitor
CVE-2026-3323694 days apartNLTK has a Downloader Path Traversal Vulnerability (AFO) - Arbitrary File Overwrite
32Monitor
CVE-2026-0847110 days apartPath Traversal in nltk/nltk
30Monitor

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

Anyone who can reach it over the internet can trigger it.
No account or password is required.
No user action is required.
No special conditions are required; it is repeatable.

If successful

Confidentiality: high · data can be read
Integrity: none
Availability: none

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: Unchanged
Confidentiality impact: High
Integrity impact: None
Availability impact: None

Weakness class (CWE)

CWE-22 · Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

CVSS vector

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

nvd-secondary

Root cause

A user-supplied file name is joined with the allowed directory, but the result is never checked to confirm it is still inside that directory.

The bug in code

The whole CWE-22 class

A representative example of this vulnerability class. Not the vendor's source code; it shows the faulty pattern and its fix.

Vulnerable

1const file = path.join(ROOT, req.query.name);
2res.sendFile(file);

Fixed

1const file = path.resolve(ROOT, req.query.name);
2if (!file.startsWith(ROOT + path.sep)) {
3  return res.sendStatus(400);
4}
5res.sendFile(file);

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Attack patterns (CAPEC)

ATT&CK techniques

—

Change log

Fix✗ → ✓Sep 28, 2026, 10:46 PM UTC

For records you follow, these changes also arrive as notifications. →

References

github.com/nltk/nltk/pull/3575

Show all references (6 more)

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records