How severe is CVE-2021-24153?

CVE-2021-24153 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.

Is CVE-2021-24153 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-24153?

CVE-2021-24153 affects Yoast Yoast Seo. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2021-24153?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2021-24153 published?

CVE-2021-24153 was published on 2021-04-05 and last updated on 2026-06-17.

CVE-2021-24153

CVE-2021-24153 is a medium-severity vulnerability in Yoast Yoast Seo with a CVSS 3.x base score of 5.4. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-79.

Key facts

Severity: Medium (CVSS 3.x base score 5.4)
CVSS v2: 3.5
EPSS exploit prediction: 1% (62nd percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-79
Affected product: Yoast Yoast Seo
Published: 2021-04-05
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-24153?: 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.
How severe is CVE-2021-24153?: CVE-2021-24153 has a CVSS 3.x base score of 5.4, rated medium severity. It is exploitable over network with low attack complexity, requires low privileges and user interaction. Impact on confidentiality is low, integrity low, and availability none.
Is CVE-2021-24153 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (62nd percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-24153?: CVE-2021-24153 affects Yoast Yoast Seo. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2021-24153?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2021-24153 published?: CVE-2021-24153 was published on 2021-04-05 and last updated on 2026-06-17.

References

Affected products (1)

cpe:2.3:a:yoast:yoast_seo:*:*:*:*:*:wordpress:*:*

More vulnerabilities in Yoast Yoast Seo

CVE-2019-13478 — Critical (CVSS 9.8): The Yoast SEO plugin before 11.6-RC5 for WordPress does not properly restrict unfiltered HTML in term descriptions.
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CVE-2018-19370 — Medium (CVSS 6.6): A Race condition vulnerability in unzip_file in admin/import/class-import-settings.php in the Yoast SEO (wordpress-seo)…
CVE-2023-28785 — Medium (CVSS 6.5): Auth. (contributor+) Stored Cross-Site Scripting (XSS) vulnerability in Yoast Yoast SEO: Local plugin <= 14.9 versions.
CVE-2021-31779 — Medium (CVSS 6.4): The yoast_seo (aka Yoast SEO) extension before 7.2.1 for TYPO3 allows SSRF via a backend user account.
CVE-2023-40680 — Medium (CVSS 5.9): Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Team Yoast Yoast…

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