CVE-2021-24556Public exploitNetwork attack vector

Stored XSS via unescaped subscriber database fields

Published Aug 23, 2021 · Updated Aug 3, 2024

Stored XSS in KentoThemes Email Subscriber 1.1 and earlier allows remote attackers to execute JavaScript in an administrator's browser. The kento_email_subscriber_ajax action stores unvalidated subscribe_email and subscribe_name POST values, and the Subscriber list prints them without output escaping. Exploitation requires no account, but an administrator must open the list; the script then runs with that browser session's access to the WordPress administration interface.

CVSS severity6.1
Medium
EPSS probability1.34%
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 KentoThemes Email Subscriber 1.1 and earlier allows remote attackers to execute JavaScript in an administrator's browser. The kento_email_subscriber_ajax action stores unvalidated subscribe_email and subscribe_name POST values, and the Subscriber list prints them without output escaping. Exploitation requires no account, but an administrator must open the list; the script then runs with that browser session's access to the WordPress administration interface.

The record

CVE
CVE-2021-24556
Published
Aug 23, 2021
Updated
Aug 3, 2024
Vendor
KentoThemes
Product
Email Subscriber
Classifications
CWE-79, T1203
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 23, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 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=1.1 <=1.1

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

KentoThemes · Email Subscriberversion=1.1 <=1.1

Published CVSS scores

6.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
4.3NIST NVDAV:N/AC:M/Au:N/C:N/I:P/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 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')
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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