Yoast Seo
CVE-2021-24153
MEDIUM
Vulnerability Assessment
| Weakness |
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK
2 techniques across 2 tactics: Initial Access, Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. |
| Impact | CVSS score of 5.4 (MEDIUM). Attack characteristics: network attack vector, low complexity, low privileges required, user interaction required. Public proof-of-concept exploit code is available. |
| Exploit ScenarioDerived | A remote attacker could inject malicious scripts into web pages viewed by other users by sending crafted requests to the affected application. |
Get an e-mail when this CVE is exploited, patched or re-scored. Free account.
Alert meAnalysisAI
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. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, low attack complexity. Public exploit code available and no vendor patch available.
RemediationAI
No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Sanitize all user input, use Content-Security-Policy headers, encode output contextually (HTML, JS, URL). Use frameworks with built-in XSS protection.
Affects your stack
Find out whether the stacks and servers you run are on an affected version.
Checking this CVE against your own stacks and servers is part of the Basic plan and up.
Technical ContextAI · show details
This vulnerability is classified as Cross-Site Scripting (XSS) (CWE-79), which allows attackers to inject malicious scripts into web pages viewed by other users. 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. Affected products include: Yoast Yoast Seo. Version information: before 3.4.1.
Severity by source
AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N
Primary rating from NVD · only source for this CVE.
CVSS VectorNVD
DescriptionNVD
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.
Threat Intelligence Overview
NVD
CVE.org
EPSS
How this decision was reached
The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.
What every action level means
SSVC AssessmentENISA
Priority Score
Attack Technique
Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.
Affected Products (CPE)NVD
A Race condition vulnerability in unzip_file in admin/import/class-import-settings.php in the Yoast SEO (wordpress-seo)
The Yoast SEO plugin before 11.6-RC5 for WordPress does not properly restrict unfiltered HTML in term descriptions. Rate
The yoast_seo (aka Yoast SEO) extension before 7.2.1 for TYPO3 allows SSRF via a backend user account. Rated medium seve
Unauth. Rated medium severity (CVSS 6.1), this vulnerability is remotely exploitable, no authentication required, low at
Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') vulnerability in Team Yoast Yoast S
Auth. Rated medium severity (CVSS 5.4), this vulnerability is remotely exploitable, low attack complexity. No vendor pat
The yoast_seo (aka Yoast SEO) extension before 7.2.3 for TYPO3 allows XSS. Rated medium severity (CVSS 5.4), this vulner
GitHub PoC
Exploit-DB