An issue was discovered in Qt before 5.15.14, 6.x before 6.2.9, and 6.3.x through 6.5.x before 6.5.1. Qt Network incorrectly parses the strict-transport-security (HSTS) header, allowing unencrypted connections to be established, even when explicitly prohibited by the server. This happens if the case used for this header does not exactly match.
An issue was discovered in Qt 5.x before 5.15.14, 6.x before 6.2.9, and 6.3.x through 6.5.x before 6.5.1. QDnsLookup has a buffer over-read via a crafted reply from a DNS server.
Qt before 6.4.3 allows a denial of service via a crafted string when the SQL ODBC driver plugin is used and the size of SQLTCHAR is 4. The affected versions are 5.x before 5.15.13, 6.x before 6.2.8, and 6.3.x before 6.4.3.
In Qt 5.9.x through 5.15.x before 5.15.9 and 6.x before 6.2.4 on Linux and UNIX, QProcess could execute a binary from the current working directory when not found in the PATH.