According to Trend Micro, “We’re not aware of any active attacks against these vulnerabilities currently. But the only way to protect your Windows systems from potential attacks against these or other vulnerabilities in Apple QuickTime now is to uninstall it.” They also note that since the app is seemingly no longer being updated, uninstalling it seems to be the best way to deal with the problem.
In fact Trend Micro is not alone in their assessment. The US government’s Computer Emergency Readiness Team has also caught wind of the problem and have agreed with Trend Micro in that uninstalling QuickTime is the best way to go about the issue for now.
According to their recommendation, “Computers running QuickTime for Windows will continue to work after support ends. However, using unsupported software may increase the risks from viruses and other security threats. Potential negative consequences include loss of confidentiality, integrity, or availability of data, as well as damage to system resources or business assets. The only mitigation available is to uninstall QuickTime for Windows.”
Note that this only seems to apply to the Windows version of the app as the Mac version of QuickTime does not feature the same flaws, presumably because it is still being updated until today.