YesWiki is a wiki system written in PHP. Prior to version 4.5.4, YesWiki is vulnerable to reflected XSS in the file upload form. This vulnerability allows any malicious unauthenticated user to create a link that can be clicked on by the victim to perform arbitrary actions. This issue has been patched in version 4.5.4.
https://github.com/YesWiki/yeswiki/security/advisories/GHSA-2f8p-qqx2-gwr2
https://github.com/YesWiki/yeswiki/pull/1264/commits/6edde40eb7eeb5d60619ac4d1e0a0422d92e9524