Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Cross-site scripting (XSS) vulnerability in PHP Handicapper allows remote attackers to inject arbitrary web script or HTML via the msg parameter to msg.php. NOTE: some sources identify a second vector in the login parameter to process_signup.php, but the original source says that it is for CRLF injection (CVE-2005-4712). Also note: the vendor has disputed CVE-2005-3497, and it is possible that the dispute was intended to include this issue as well. If so, followup investigation strongly suggests that the original report is correct.
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.