We have just released zcashd version 2.0.7-3 which includes an important security fix in response to an issue that was reported to us on Friday September 13th 2019 by Florian Tramèr, Dan Boneh, and Kenneth G. Paterson.
All operators of zcashd should upgrade their nodes ASAP. Security Announcement 2019-09-24 - Zcash
Please note that the issue does not put funds at risk of theft or counterfeiting. More details of the issue will be released in coordination with the reporters of the issue at a future date.