Grav: detectXss() misses an event-handler attribute after an unpaired quote in an unquoted attribute value, giving stored XSS

Affected versions and vulnerable location - Confirmed on grav core at 78ebfc1 tag 2.0.13. - Detector: system/src/Grav/Common/Security.php:290, the onevents regex, run via patternMatches :315-330. - The onevents pattern at HEAD: "'??:\s\x00-\x20"'/|"^""|'^''on\sa-z+\s=iu - Sole save-time guard for...