com.xwiki.identity-oauth:identity-oauth-ui is a package to aid in building identity and service providers based on OAuth authorizations. When a user logs in via the OAuth method, the identityOAuth parameters sent in the GET request is vulnerable to cross site scripting (XSS) and XWiki syntax injection. This allows remote code execution via the groovy macro and thus affects the confidentiality, integrity and availability of the whole XWiki installation. The issue has been fixed in Identity OAuth version 1.6. There are no known workarounds for this vulnerability and users are advised to upgrade.