CVE-2026-6879 Quadratic Behavior in xml.etree.ElementPath Index Predicates

Element.findall and fully-consumed Element.iterfind exhibit On^2 time complexity when using XPath index predicates e.g. 1, last, last-N on XML documents with many same-tag siblings. Element.find is only affected when the first match is near the end of the sibling list, such as with last or...