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.
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.
A keystroke logging issue was discovered in Virtual Keyboard in Qt 5.7.x, 5.8.x, 5.9.x, 5.10.x, and 5.11.x before 5.11.3.
The named pipes in qtsingleapp in Qt 5.x, as used in qBittorrent and SugarSync, are configured for remote access and allow remote attackers to cause a denial of service (application crash) via an unspecified string.