f.lux suffers from a DLL hijacking vulnerability.
"flux-setup.exe" loads and executes dll from its "application directory".
For software downloaded with a web browser the applicationdirectory is
typically the user's "Downloads" directory: see <
and <http://seclists.org/fulldisclosure/2012/Aug/134> for "prior art" about
this well-known and well-documented vulnerability.
If an attacker places malicious DLL in the user's "Downloads" directory
(for example per "drive-by download" or "social engineering") this
vulnerability becomes a remote code execution.
Proof of concept/demonstration:
1. Create a malicious dll file and save it in your "Downloads" directory.
2. Download "flux-setup.exe" from https://justgetflux.com/ and save it in
your "Downloads" directory.
3. Execute "flux-setup.exe" from your "Downloads" directory.
4. Malicious dll file gets executed.
Fixes will be available in next build.