CVE.org (no NVD analysis yet)· CNA VulnCheck

CVE-2026-109956: NLTK through 3.10.3 Path Traversal via WekaClassifier Model Path

HighCVSS 8.3 · v4.0—No exploit Fix available

Noroxi assessment

Priority: Monitor (action score 33/100)

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: 0.31% (FIRST EPSS).
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.
Fixed version: nltk (PyPI) 3.10.4.

Low priority for now. Upgrade to nltk (PyPI) 3.10.4 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 through 3.10.3 contains a path traversal vulnerability in WekaClassifier that allows attackers to bypass nltk.pathsec containment by supplying unvalidated model paths. Attackers controlling the model_filename or model argument can make the weka JVM write files via -d or probe files via -l outside allowed data roots.

Published: Oct 13, 2026
Updated: Oct 26, 2026
EPSS: 0.3% · 25th percentile
CWE: CWE-22

Report tools

JSON

Action score

Monitor

Low priority for now.

CVSS: 33 / 40 · 8.3 / 10
CISA KEV: 0 / 30 · Not listed
EPSS: 0 / 30 · 0.3%

CISA SSVC decision

Exploitation: proof of concept
Automatable: no
Technical impact: partial

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD: —
CNA · VulnCheck: 8.3; NVD has not scored this yet; the score shown is the CNA’s.

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N

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.

Is your version affected? Check it

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.

—

Versions reported by the vendor

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

nltk nltk
- up to and including 3.10.3affected · semver

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	—
PyPI	nltk	before 3.10.4	3.10.4

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-2026-81727Aug 27, 2026 · NLTK before 3.10.3 Hardlink File Overwrite via downloader
27Monitor
← EarlierCVE-2026-81726Aug 27, 2026 · NLTK through 3.10.3 Path Traversal via Model-Artifact APIs
33Monitor
Later →CVE-2026-126295Nov 13, 2026 · NLTK 3.10.0 before 3.10.4 Arbitrary File Read via BllipParser Model Paths
28Monitor

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
PyPI:nltk	3.10.4	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.

PublishedOct 13, 2026
Fix recordedOct 27, 2026+14 d
TodayNov 13, 2026+31 d

EPSS, last 120 days

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

Credits

All researchers

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

manus-usereporter

Variant candidates

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

CVE-2026-6238452 days apartNLTK FramenetCorpusReader Symlink Sandbox Bypass before 3.10.2
34Monitor
CVE-2026-6331252 days apartNLTK StreamBackedCorpusView Bypasses pathsec.ENFORCE Arbitrary File Read
34Monitor
CVE-2026-7967649 days apartNLTK before 3.10.3 Path Traversal via Symlink Bypass
32Monitor
CVE-2026-33236207 days apartNLTK has a Downloader Path Traversal Vulnerability (AFO) - Arbitrary File Overwrite
32Monitor
CVE-2026-54293113 days apartNLTK: URL-Encoded Path Traversal in nltk.data.load() Allows Arbitrary Local File Read
30Monitor
CVE-2026-0847223 days apartPath Traversal in nltk/nltk
30Monitor

Not on record for this CVE: patch commit or PR link · public bounty program.

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
Integrity
Availability

Attack vector: Network
Attack complexity: Low
Privileges required: None
User interaction: None
Scope: X

Weakness class (CWE)

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

CVSS vector

CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:L/VI:H/VA:L/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X

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✗ → ✓Oct 27, 2026, 4:07 PM UTC
SSVC exploitation— → pocOct 26, 2026, 9:07 PM UTC
Exploit maturity— → noneOct 13, 2026, 3:07 PM UTC

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

References

github.com/nltk/nltk/security/advisories/GHSA-j456-xh4h-cpf2

Show all references (1 more)

www.vulncheck.com/advisories/nltk-through-3.10.3-path-traversal-via-wekaclassifier-model-path

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

All records