TwsCachedXPathAPI in Convertigo versions before 8.3.11 did not restrict commons-jxpath functions, which could allow expression injection in contexts where an attacker can influence an evaluated XPath expression. Convertigo 8.3.11 fixes the issue by assigning an empty FunctionLibrary to JXPath contexts.
https://github.com/convertigo/convertigo/releases/tag/8.3.11
https://github.com/convertigo/convertigo/issues/898
https://github.com/convertigo/convertigo/commit/431d1bfeb360a55f4ed299cc3aa287cc5c6357e1
https://github.com/convertigo/convertigo/blob/8.3.11/CHANGELOG.md#8311