Description
Drupal Core is prone to a cross-site scripting vulnerability because it fails to properly sanitize user-supplied input. An attacker may leverage this issue to execute arbitrary script code in the browser of an unsuspecting user in the context of the affected site. This can allow the attacker to steal cookie-based authentication credentials and launch other attacks. Drupal Core versions 8.9.x ranging from 8.9.0 and up to and including 8.9.17 are vulnerable.
Remediation
Update to Drupal Core version 8.9.18 or latest
References
https://www.drupal.org/sa-core-2021-005
https://ckeditor.com/blog/ckeditor-4.16.2-with-browser-improvements-and-security-fixes/
Related Vulnerabilities
TYPO3 Exposure of Sensitive Information to an Unauthorized Actor Vulnerability (CVE-2009-3628)
Joomla! Core 3.x.x Security Bypass (3.2.0 - 3.4.4)
IBM WebSEAL Use of a Broken or Risky Cryptographic Algorithm Vulnerability (CVE-2019-4156)
Oracle Database Server CVE-2006-0291 Vulnerability (CVE-2006-0291)
WordPress Plugin Social Connect Cross-Site Scripting (1.0.4)