Google's Project Zero has found a vulnerability in Windows 10, and they've taken it upon themselves to expose it. The vulnerability lies in the gdi32.dll file that is used by a significant amount of programs. To go over the gritty technical details would be overkill, but if you're the sort of person who can comb through programming jargon, you're free to read the full report here.
For those who don't know, Google's Project Zero is a group in Google dedicated to identifying zero day vulnerabilities in the hopes that they can find them before truly malicious people can. In the event that Project Zero finds a vulnerability, they report it to the software manufacturer and give them 90 days to fix the issue. If the issue isn't fixed in that time frame, Project Zero will make the report publicly available so that users can protect themselves.
Microsoft hasn't yet commented on the now-public report of the exploit, so we aren't sure when a fix is coming. It's entirely possible that the fix could have been on its way in this month's Patch Tuesday, but that patch has been delayed to March 14th.
This exploit isn't particularly nasty, so - in theory - you shouldn't have to worry too much about it. Hopefully, the hole will be plugged sooner rather than later so we can all feel a bit better about our safety on Windows 10.