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


Severity Medium
Score 6.1/10


Sanitize is an allowlist-based HTML and CSS sanitizer. Versions 5.0.0 through 6.0.0 are vulnerable to Cross-site Scripting. When Sanitize is configured with a custom allowlist that allows "noscript" elements, attackers are able to include arbitrary HTML, resulting in XSS (cross-site scripting) or other undesired behaviour when that HTML is rendered in a browser. The default configurations do not allow "noscript" elements and are not vulnerable. This issue only affects users who are using a custom config that adds "noscript" to the element allowlist. Users who are unable to upgrade can prevent this issue by using one of Sanitize's default configs or by ensuring that their custom config does not include "noscript" in the element allowlist.

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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