MacRumors posted a story that Apple seeded the third beta of OS X 10.10.5 to developers

The first and second OS X 10.10.5 betas did not appear to include any consumer-facing changes, so it's likely that this update focuses on behind-the-scenes bug fixes and performance enhancements. OS X 10.10.5 beta 2 introduced a fix for the DYLD_PRINT_TO_FILE exploit that's been making headlines over the last few days, and the security flaw will be patched as soon as OS X 10.10.5 is released to the public. Because we're just a couple of months away from the public release of OS X 10.11 El Capitan, OS X 10.10.5 will likely be one of the last updates to Yosemite, designed to prepare the operating system for its imminent retirement.

  Apple Seeds Third OS X 10.10.5 Yosemite Beta to Developers