Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
The cross-site scripting (XSS) prevention feature in Ruby on Rails 2.x before 2.3.12, 3.0.x before 3.0.8, and 3.1.x before 3.1.0.rc2 does not properly handle mutation of safe buffers, which makes it easier for remote attackers to conduct XSS attacks via crafted strings to an application that uses a problematic string method, as demonstrated by the sub method.
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.