Description Contao >=4.0.0 allows backend XSS via HTML attributes to an HTML field. Fixed in 4.4.56, 4.9.18, 4.11.7. Remediation References CVE-2021-35955 Related Vulnerabilities Pega Infinity Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') Vulnerability (CVE-2023-4843) Dotclear Permissions, Privileges, and Access Controls Vulnerability (CVE-2011-5083) Sqlite Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal') Vulnerability (CVE-2008-6592) IBM WebSEAL Improper Input Validation Vulnerability (CVE-2019-4036) Opencart Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') Vulnerability (CVE-2024-21516) Severity Medium Classification CVE-2021-35955 CWE-707 CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N Tags Missing Update Known Vulnerabilities