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


Severity High
Score 9/10


XWiki Commons are technical libraries common to several other top-level XWiki projects. The "restricted" mode of the HTML cleaner in XWiki, in versions 4.2-milestone-1 through 14.9, allowed the injection of arbitrary HTML code and thus cross-site scripting via invalid HTML comments. As a consequence, any code relying on this "restricted" mode for security is vulnerable to JavaScript injection ("cross-site scripting"/XSS). When a privileged user with programming rights visits such a comment in XWiki, the malicious JavaScript code is executed in the context of the user session. This allows server-side code execution with programming rights, impacting the confidentiality, integrity, and availability of the XWiki instance. HTML comments are now removed in restricted mode and a check has been introduced that ensures that comments don't start with `>`. There are no known workarounds apart from upgrading to a version including the fix.

  • LOW
  • HIGH
  • LOW
  • HIGH
  • HIGH

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