CVE-2021-24153

Name: CVE-2021-24153
Creator: NVD / NIST
Published: 2021-04-05T19:15:14.56+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.4/10EPSS 1.11%

Last modified Jun 17, 2026

CVE-2021-24153 is a medium-severity vulnerability rated 5.4/10 on the CVSS scale. A Stored Cross-Site Scripting vulnerability was discovered in the Yoast SEO WordPress plugin before 3.4.1, which had built-in blacklist filters which were blacklisting Parenthesis as well as several functions such as alert but bypasses were found.. EPSS estimates a 1.11% chance of exploitation in the next 30 days.

Description

A Stored Cross-Site Scripting vulnerability was discovered in the Yoast SEO WordPress plugin before 3.4.1, which had built-in blacklist filters which were blacklisting Parenthesis as well as several functions such as alert but bypasses were found.

Metrics

CVSS 3.1

5.4/10

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

EPSS Probability

1.11%

61.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Yoast	Yoast Seo	< 3.4.1

References

https://packetstormsecurity.com/files/138192/Exploit, Third Party Advisory, VDB Entry
https://plugins.trac.wordpress.org/changeset/1466243/wordpress-seoThird Party Advisory
https://wpscan.com/vulnerability/77810044-394d-4314-b9a1-20c7dca726dcThird Party Advisory
https://packetstormsecurity.com/files/138192/Exploit, Third Party Advisory, VDB Entry
https://plugins.trac.wordpress.org/changeset/1466243/wordpress-seoThird Party Advisory
https://wpscan.com/vulnerability/77810044-394d-4314-b9a1-20c7dca726dcThird Party Advisory

Timeline

Published: Apr 5, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-24153?

How severe is CVE-2021-24153?

CVE-2021-24153 has a CVSS score of 5.4/10 (MEDIUM severity). The EPSS model estimates a 1.11% probability of exploitation in the next 30 days.

How do I fix CVE-2021-24153?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-24153?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST