If you are still using QuickTime on your Windows, it is recommended you uninstalled them and switch to another player as soon as you can. Even the US government has issued a warning for all users to uninstall it from their Windows based computer.
Trend Micro has recently found 2 vulnerabilities with the Windows’ version of QuickTime that have significant impact on security. The two new vulnerabilities are heap-corruption-based remote code execution vulnerabilities, which essentially means that an attacker could gain access to a user’s computer by tricking them in to downloading a file from the web. While there’s nothing currently taking advantage of this hole, now that it is out in the open, it shouldn’t be too much longer.
However when told of the vulnerabilities, Apple reportedly told Trend Micro recently that “the product would be deprecated on Windows and the vendor would publish removal instructions for users.”
You can still continue to run QuickTime on your Windows after support for it has ended. 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 best option now is to uninstall QuickTime from your Windows.