Email Subscriber <= 1.1 - Unauthenticated Stored Cross-Site Scripting (XSS)

published 2021-08-23 5 y ago modified 2026-06-17 4 mo ago also EUVD-2021-11468

cvss: 6.1; version 3.1, NVD
cisa kev: Not listed; not in CISA's catalog
epss: 1.3%; EPSS 1.3% chance of exploitation in 30 days, percentile 71%
public exploits: 0; none known

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.

Exploit prediction

1.34% chance of exploitation in the next 30 days, higher than 71% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

wpscan.com https://wpscan.com/vulnerability/f050aedc-f79f-4b27-acac-0cdb33b25af8 referenced PoC, tagged "exploit" by a source, unverified
codevigilant.com https://codevigilant.com/disclosure/2021/wp-plugin-email-subscriber/ referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by	version	score	vector
NVD	3.1	6.1	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N
NVD	2.0	4.3	AV:N/AC:M/Au:N/C:N/I:P/A:N

Affected products

Unknown Email Subscriber

Classification

Weakness

CWE-79 Improper Neutralization of Input During Web Page Generation

Technology feeds

WordPress rss critical rss

References

wpscan.com /vulnerability/f050aedc-f79f-4b27-acac-0cdb33b25af8
exploit, third-party-advisory
codevigilant.com /disclosure/2021/wp-plugin-email-subscriber/
exploit, third-party-advisory

Sources

CVE List CVE-2021-24556
NVD CVE-2021-24556

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

Summary