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.

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