Luca Todesco shared information (via AppleInsider) on the "tpwn" exploit on GitHub over the weekend. It affects all versions of OS X Yosemite, including OS X 10.10.5, but does not affect OS X El Capitan.
Todesco did not give Apple a heads up on the vulnerability before sharing it publicly, so it is not clear when Apple will release a patch for machines running OS X Yosemite. As noted by AppleInsider, it is standard procedure (and a courtesy) for security researchers and developers to provide Apple with details on vulnerabilities before publicizing them to prevent hackers from using security holes for nefarious purposes.
According to Todesco, who has also shared what he says is a third-party fix, releasing details on the exploit is no different than releasing an iOS jailbreak, but as Engadget explains, Todesco's actions have the potential to be somewhat more harmful than a jailbreak.
Those are technically true, but they downplay the practical dangers of publishing this info. Many people aren't knowledgeable enough to try third-party safeguards or deal with the possible side effects, and jailbreaks are at least intended for semi-innocuous purposes. A 'surprise' exploit for the Mac only really serves to give attackers time that they wouldn't otherwise have.It took Apple less than a month to release OS X 10.10.5 to fix the DYLD_PRINT_TO_ACCESS vulnerability after it was first publicized, but during the time between its discovery and the launch of the fix, an exploit using the vulnerability was discovered in the wild.
Ahead of a fix for this latest vulnerability, OS X Yosemite users can protect themselves by downloading apps solely from the Mac App Store and from trusted developers.