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 WordPress Plugin TemplatesNext ToolKit Cross-Site Scripting (3.2.8) phpMyAdmin Improper Input Validation Vulnerability (CVE-2013-5029) PHP Double Free Vulnerability (CVE-2016-3132) Apache HTTP Server Improper Input Validation Vulnerability (CVE-2011-4415) WordPress 4.0.x Multiple Vulnerabilities (4.0 - 4.0.28) 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