MPM Guestbook is reported to be prone to a cross-site scripting vulnerability. This is due to insufficient sanitization of HTML from URI parameters, which will be displayed in web pages that are dynamically generated by the software.
An attacker could exploit this issue by enticing a user to follow a malicious link. This could theoretically allow for theft of cookie-based authentication credentials or other attacks.
MPM Guestbook contains a flaw that allows a remote cross site scripting attack. This flaw exists because the application does not validate the "ing" variable upon submission to the script. This could allow a user to create a specially crafted URL that would execute arbitrary code in a user's browser within the trust relationship between the browser and the server, leading to a loss of integrity.
Currently, there are no known upgrades, patches, or workarounds available to correct this issue.