{"cve":"CVE-2021-24153","nvd":{"published":"2021-04-05T19:15:14.560","modified":"2026-06-17T03:39:29.040","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N","score":5.4},"cwes":["CWE-79"],"references":["https://packetstormsecurity.com/files/138192/","https://plugins.trac.wordpress.org/changeset/1466243/wordpress-seo","https://wpscan.com/vulnerability/77810044-394d-4314-b9a1-20c7dca726dc","https://packetstormsecurity.com/files/138192/","https://plugins.trac.wordpress.org/changeset/1466243/wordpress-seo"],"products":["yoast:yoast_seo"],"source":"nvd","synced_at":"2026-10-19T21:17:01.373894544+00:00"},"epss":{"cve":"CVE-2021-24153","score":0.01115,"percentile":0.66069,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}