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).
The Google V8 engine, as used in Google Chrome before 44.0.2403.89 and QtWebEngineCore in Qt before 5.5.1, allows remote attackers to cause a denial of service (memory corruption) or execute arbitrary code via a crafted web site.
The GIF decoder in QtGui in Qt before 5.3 allows remote attackers to cause a denial of service (NULL pointer dereference) via invalid width and height values in a GIF image.
SQL injection vulnerability in Quassel IRC before 0.9.1, when Qt 4.8.5 or later and PostgreSQL 8.2 or later are used, allows remote attackers to execute arbitrary SQL commands via a \ (backslash) in a message.
The QSharedMemory class in Qt 5.0.0, 4.8.x before 4.8.5, 4.7.x before 4.7.6, and other versions including 4.4.0 uses weak permissions (world-readable and world-writable) for shared memory segments, which allows local users to read sensitive information or modify critical program data, as demonstrated by reading a pixmap being sent to an X server.