CVE-2021-24556: The kento_email_subscriber_ajax AJAX action of the Email Subscriber WordPress plugin through 1.1, does not pro

Q: How do I fix CVE-2021-24556?

email-subscriber: upgrade to newer than 1.1. Exact commands for each OS are on this page.

Q: Is CVE-2021-24556 being exploited?

CVE-2021-24556 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

Q: What does CVE-2021-24556 affect?

CVE-2021-24556 affects email-subscriber. Severity is medium (CVSS 6.1). The kento_email_subscriber_ajax AJAX action of the Email Subscriber WordPress plugin through 1.1, does not properly sanitise, validate and escape the submitted subscribe_email and subscribe_name POST parameters, inserting them in the DB and

Q: How urgent is CVE-2021-24556?

Priority 44/100. Public exploit reference

This month

MEDIUM 6.1UPGRADE

CVE-2021-24556 is a medium-severity flaw (CVSS 6.1) affecting email-subscriber. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

The kento_email_subscriber_ajax AJAX action of the Email Subscriber WordPress plugin through 1.1, does not properly sanitise, validate and escape the submitted subscribe_email and subscribe_name POST parameters, inserting them in the DB and then outputting them back in the Subscriber list (/wp-admin/edit.php?post_type=kes_campaign&page=kento_email_subscriber_list_settings), leading a Stored XSS issue.

Why this priority

Public exploit reference

A fixed release or distro patch exists.

Risk facts

CVSS score	6.1 (Medium)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	Required
EPSS exploit chance	1.3% (top 29%)
CISA exploited list	No
Weakness	CWE-79
Published	2021-08-23
Last modified	2026-06-17

Publisher (CNA): WPScan · Vendor: email-subscriber project

Last updated 2026-06-17 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-08-23 12:15 UTCPublished CVE record published
2026-06-17 03:40 UTCUpdated Record last modified

email-subscriber project email-subscriber UPGRADE

Affected: <= 1.1

Fixed in: newer than 1.1

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy email-subscriber || rpm -q email-subscriber || email-subscriber --version

2. UPGRADE to newer than 1.1 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade email-subscriber

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade email-subscriber

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-24556?

email-subscriber: upgrade to newer than 1.1. Exact commands for each OS are on this page.

Is CVE-2021-24556 being exploited?

CVE-2021-24556 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2021-24556 affect?

CVE-2021-24556 affects email-subscriber. Severity is medium (CVSS 6.1). The kento_email_subscriber_ajax AJAX action of the Email Subscriber WordPress plugin through 1.1, does not properly sanitise, validate and escape the submitted subscribe_email and subscribe_name POST parameters, inserting them in the DB and

How urgent is CVE-2021-24556?

Priority 44/100. Public exploit reference

Software pages

WordPress vulnerabilities · PHP vulnerabilities

References

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