Project Zero works to discover security vulnerabilities of various operating systems and software, giving their owners 90 days notice to patch the issues before publishing their findings to the public. In their markup of Apple's OS X, problems involving memory corruption, kernel code execution, and a sandbox escape were all discovered by the team. Ars Technica notes:
At first glance, none of them appear to be highly critical, since all three appear to require the attacker to already have some access to a targeted machine. [...]As the 90-day deadline hit during the week, the group began posting its findings online. Google's notes suggest one of the vulnerabilities was fixed with the release of OS X Yosemite, while the other two remained unaddressed.
Still, the exploits could be combined with a separate attack to elevate lower-level privileges and gain control over vulnerable Macs. And since the disclosures contain proof-of-concept exploit code, they provide enough technical detail for experienced hackers to write malicious attacks that target the previously unknown vulnerabilities.
But as pointed out by iMore, Apple's incoming OS X 10.10.2 update does indeed include fixes for the