CVE-2021-39202Network attack vector

Stored XSS via unneutralized Custom HTML

Published Sep 9, 2021 · Updated Aug 4, 2024

Stored XSS in the Custom HTML widget in WordPress 5.8 beta 1 through 5.8 beta 2 allows remote authenticated users to run scripts. The beta widgets editor stores Custom HTML input without correctly neutralizing script-related HTML before rendering the widget. High-privilege widget-editing access is required; injected script runs for visitors who load the affected widget and can read or alter data in their browser session.

CVSS severity3.8
Low
EPSS probability0.82%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stored XSS in the Custom HTML widget in WordPress 5.8 beta 1 through 5.8 beta 2 allows remote authenticated users to run scripts. The beta widgets editor stores Custom HTML input without correctly neutralizing script-related HTML before rendering the widget. High-privilege widget-editing access is required; injected script runs for visitors who load the affected widget and can read or alter data in their browser session.

The record

CVE
CVE-2021-39202
Published
Sep 9, 2021
Updated
Aug 4, 2024
Vendor
WordPress.org
Product
WordPress
Classifications
CWE-80, T1059.007
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Sep 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record 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=5.8 beta 1
  2. Affected versionversion=5.8 beta 2

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

WordPress.org · WordPressversion=5.8 beta 1; version=5.8 beta 2

Published CVSS scores

3.8GitHubCVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:U/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-80Improper Neutralization of Script-Related HTML Tags in a Web Page (Basic XSS)
T1059.007JavaScript/JScript

Public exploit references

No public exploit references are available in this record.

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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