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Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')


Severity Medium
Score 6.1/10


Symfony is a PHP framework for web and console applications and a set of reusable PHP components. In versions 2.0.4 through 4.4.50, 5.0.0-BETA1 through 5.4.30, 6.0.0-BETA1 through 6.3.7, 6.4.0-BETA1 through 6.4.0-BETA2, and 7.0.0-BETA1 through 7.0.0-BETA2 some Twig filters in "CodeExtension" use `is_safe=html` but don't actually ensure their input is safe. In the fixed versions, Symfony now escapes the output of the affected filters.

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CWE-79 - Cross Site Scripting

Cross-Site Scripting, commonly referred to as XSS, is the most dominant class of vulnerabilities. It allows an attacker to inject malicious code into a pregnable web application and victimize its users. The exploitation of such a weakness can cause severe issues such as account takeover, and sensitive data exfiltration. Because of the prevalence of XSS vulnerabilities and their high rate of exploitation, it has remained in the OWASP top 10 vulnerabilities for years.

Advisory Timeline

  • Published