CVE-2025-5991

There is a “Use After Free” vulnerability in Qt’s QHttp2ProtocolHandler in the QtNetwork module. This only affects HTTP/2 handling, HTTP handling is not affected by this at all. This happens due to a race condition between how QHttp2Stream uploads the body of a
POST request and the simultaneous handling of HTTP error responses.

This issue only affects Qt 6.9.0 and has been fixed for Qt 6.9.1.

Assigner : security@qt.io

More information : https://codereview.qt-project.org/c/qt/qtbase/+/643777