An issue was found in the private API function qDecodeDataUrl() in QtCore, which is used in QTextDocument and QNetworkReply, and, potentially, in user code.

If the function was called with malformed data, for example, an URL that
contained a "charset" parameter that lacked a value (such as
"data:charset,"), and Qt was built with assertions enabled, then it would hit an assertion, resulting in a denial of service
(abort).

This impacts Qt up to 5.15.18, 6.0.0->6.5.8, 6.6.0->6.8.3 and 6.9.0. This has been fixed in 5.15.19, 6.5.9, 6.8.4 and 6.9.1.