bunkerweb is an Open-source and next-generation Web Application Firewall (WAF). A open redirect vulnerability exists in the loading endpoint, allowing attackers to redirect authenticated users to arbitrary external URLs via the "next" parameter. The loading endpoint accepts and uses an unvalidated "next" parameter for redirects. Ex. visiting: "/loading?next=https://google.com" while authenticated will cause the page will redirect to google.com. This vulnerability could be used in phishing attacks by redirecting users from a legitimate application URL to malicious sites. This issue has been addressed in version 1.5.11. Users are advised to upgrade. There are no known workarounds for this vulnerability.