XWiki Platform is a generic wiki platform offering runtime services for applications built on top of it. Versions 7.0-milestone-2 through 16.10.11, 17.0.0-rc-1 through 17.4.4, and 17.5.0-rc-1 through 17.7.0 contain a reflected Cross-site Scripting (XSS) vulnerability, which allows an attacker to craft a malicious URL and execute arbitrary actions with the same privileges as the victim. If the victim has administrative or programming rights, those rights can be exploited to gain full access to the XWiki installation. This issue has been patched in versions 17.8.0-rc-1, 17.4.5 and 16.10.12. To workaround, the patch can be applied manually, only a single line in templates/logging_macros.vm needs to be changed, no restart is required.