From Wikileaks' overview:
"In the wake of Edward Snowden's leaks about the NSA, the U.S. technology industry secured a commitment from the Obama administration that the executive would disclose on an ongoing basis — rather than hoard — serious vulnerabilities, exploits, bugs or "zero days" to Apple, Google, Microsoft, and other US-based manufacturers. ... "Year Zero" documents show that the CIA breached the Obama administration's commitments. Many of the vulnerabilities used in the CIA's cyber arsenal are pervasive and some may already have been found by rival intelligence agencies or cyber criminals."
By not releasing this information to technology companies affected, they are increasing the risk of the same exploits being used against high profile US targets.