Stored XSS in PluXml CMS

PluXml CMS is vulnerable to Stored XSS in Static Pages editing functionality. Attacker with editing privileges can inject arbitrary HTML and JS into website, which will be rendered/executed when visiting edited page. The vendor was notified early about this vulnerability, but didn't respond with the details of vulnerability or vulnerable version range. Only versions 5.8.21 and 5.9.0-rc7 were tested and confirmed as vulnerable, other versions were not tested and might also be vulnerable.