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Yoast SEO <= 3.4.0 — Authenticated Stored Cross-Site Scripting

CVE-2021-24153Published · Updated

Action summary

Affected: <3.4.1Update to 3.4.1 or newer

All remediation steps
Watch plugin
Severity
Medium5.4
CVSS
5.4
CVSS 3.1 · CNA (Wordfence)
CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
What does this vector mean?
AV:N Attack vector
Network
AC:L Attack complexity
Low
PR:L Privileges required
Low
UI:R User interaction
Required
S:C Scope
Changed
C:L Confidentiality
Low
I:L Integrity
Low
A:N Availability
None
Weakness
CWE-79 Cross-Site Scripting
Required access
Unknown
Exploit prediction (EPSS)
No score
CISA KEV
Not listed
On this page8

Am I affected?

Yoast SEO – Advanced SEO with real-time guidance and built-in AI wordpress-seo

  1. Affected< 3.4.1
  2. Patched in3.4.1

Update to 3.4.1 or newer.

You are affected if you run < 3.4.1. Version 3.4.1 and later are not affected by this issue.

  • Check your version: in wp-admin go to Plugins → Installed Plugins and read the version under Yoast SEO – Advanced SEO with real-time guidance and built-in AI.
  • No admin access? Run a passive check of your site. It reads public files only.

What to do

  1. Update to version 3.4.1, or a newer patched version
  2. Rotate administrator passwords and application secrets if the site ran a vulnerable version while publicly reachable.
  3. Watch Yoast SEO – Advanced SEO with real-time guidance and built-in AI to get an email when the next vulnerability is published.

Advisory

Source description from Wordfence Intelligence, credited to Hammad Shamsi.

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 parentheses as well as several functions such as alert, but bypasses were found.

Exploits & references

Proof-of-concept & detection

No public proof-of-concept or detection template is known for this vulnerability.

Advisories & patches

More in Yoast SEO – Advanced SEO with real-time guidance and built-in AI

All 20
More vulnerabilities in Yoast SEO – Advanced SEO with real-time guidance and built-in AI
SeverityVulnerabilityCVEPublished
Medium6.4Authenticated (Author+) Stored Cross-Site Scripting via Post Slug (post_name)
≤28.0Update to 28.1
CVE-2026-15425
Medium4.3Insecure Direct Object Reference to Authenticated (Contributor+) Sensitive Information Exposure via 'post_id' Parameter
≤26.5Update to 26.6
CVE-2025-14481
Medium6.4Authenticated (Contributor+) Stored Cross-Site Scripting via 'jsonText' Block Attribute
≤27.1.1Update to 27.2
CVE-2026-3427
Medium6.4Authenticated (Contributor+) Stored Cross-Site Scripting via 'yoast-schema' Block Attribute
≤26.8Update to 26.9
CVE-2026-1293
Medium6.4Authenticated (Contributor+) Stored Cross-Site Scripting
≤22.6Update to 22.7
CVE-2024-4984

Same weakness (Cross-Site Scripting)

All Cross-Site Scripting
Other Cross-Site Scripting vulnerabilities
SeverityVulnerabilityCVEPublished
High7.2Unauthenticated Stored Cross-Site Scripting via Comment User-Agent Header
EZ SQL Reports Shortcode Widget and DB Backup≤5.25.25Update to 5.26.45
CVE-2026-120688
Critical9.8Unauthenticated Arbitrary File Upload via File Upload via Public Form Submission
Chatterbug Forms – Fast, Flexible WordPress Form Builder≤1.0.2Update to 1.1
CVE-2026-125055
Critical9.8Unauthenticated PHP Object Injection to Remote Code Execution via 'form' Parameter
ELEX WordPress HelpDesk & Customer Ticketing System≤3.3.9Update to 3.4.0
CVE-2026-119077
Medium5.3Unauthenticated Sensitive Information Exposure in 'search' Parameter
Customer Reviews for WooCommerce≤5.127.0Update to 5.128.0
CVE-2026-121518

Timeline

  1. CVE published

    Severity medium, CVSS 5.4

  2. Record last updated

Sources & licenses

Wordfence record
Vulnerability data
Wordfence Intelligence. [object Object] Licensed under the CC BY-SA 4.0.
CVE® identifiers
[object Object]. Used under the CVE Program. CVE® is a registered trademark of The MITRE Corporation.
CVSS / CWE
National Vulnerability Database (NVD), shown unmodified. This product uses the NVD API but is not endorsed or certified by the NVD.
VulnCrest content
Summary, remediation guidance and page layout © VulnCrest. Not sourced from NVD.

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