An issue was discovered in Qt before 5.15.15, 6.x before 6.2.9, and 6.3.x through 6.5.x before 6.5.1. When a SVG file with an image inside it is rendered, a QTextLayout buffer overflow can be triggered.

An issue was discovered in Qt before 5.15.15, 6.x before 6.2.10, and 6.3.x through 6.5.x before 6.5.3. There are infinite loops in recursive entity expansion.

Qt through 5.14 allows an exponential XML entity expansion attack via a crafted SVG document that is mishandled in QXmlStreamReader, a related issue to CVE-2003-1564.

In Qt through 5.14.1, the WebSocket implementation accepts up to 2GB for frames and 2GB for messages. Smaller limits cannot be configured. This makes it easier for attackers to cause a denial of service (memory consumption).

Qt 5.12.2 through 5.14.2, as used in unofficial builds of Mumble 1.3.0 and other products, mishandles OpenSSL's error queue, which can cause a denial of service to QSslSocket users. Because errors leak in unrelated TLS sessions, an unrelated session may be disconnected when any handshake fails. (Mumble 1.3.1 is not affected, regardless of the Qt version.)

In Qt before 5.15.15, 6.x before 6.2.9, and 6.3.x through 6.5.x before 6.5.2, there can be an application crash in QXmlStreamReader via a crafted XML string that triggers a situation in which a prefix is greater than a length.

Qt 5.x before 5.15.6 and 6.x through 6.1.2 has an out-of-bounds write in QOutlineMapper::convertPath (called from QRasterPaintEngine::fill and QPaintEngineEx::stroke).