CVE-2026-33230Public exploitNetwork attack vector

Script execution via unescaped WordNet lookup value

Published Mar 20, 2026 · Updated Mar 20, 2026

Reflected XSS in NLTK 3.9.3 and earlier allows remote attackers to execute script in the WordNet Browser origin via a crafted lookup URL. page_from_reference inserts the decoded word value into its not-found HTML response without calling html.escape. Exploitation requires the WordNet Browser server to be running and a user to open the crafted URL; script can alter page content and issue same-origin requests.

CVSS severity6.1
Medium
EPSS probability0.33%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Reflected XSS in NLTK 3.9.3 and earlier allows remote attackers to execute script in the WordNet Browser origin via a crafted lookup URL. page_from_reference inserts the decoded word value into its not-found HTML response without calling html.escape. Exploitation requires the WordNet Browser server to be running and a user to open the crafted URL; script can alter page content and issue same-origin requests.

The record

CVE
CVE-2026-33230
Published
Mar 20, 2026
Updated
Mar 20, 2026
Vendor
NLTK Project
Product
NLTK
Classifications
CWE-79, CAPEC-591, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 20, 2026CVE publishedPublication date reported by the CVE source.
  2. Mar 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=<= 3.9.3

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

NLTK Project · NLTKversion=<= 3.9.3

Published CVSS scores

6.1GitHubCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-79Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
CAPEC-591Reflected XSS
T1203Exploitation for Client Execution

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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