Chipzilla has  issued a statement to Tom's Hardware confirming the incident saying:

"Our proprietary UEFI code appears to have been leaked by a third party. We do not believe this exposes any new security vulnerabilities as we do not rely on obfuscation of information as a security measure. This code is covered under our bug bounty program within the Project Circuit Breaker campaign, and we encourage any researchers who may identify potential vulnerabilities to bring them our attention through this programme."

 For those not in the know a BIOS/UEFI leak is a big deal because it is used to initialises the hardware before the operating system has loaded, and it is establishing connections to certain security mechanisms, like the Trusted Platform Module.

Intel hasn't confirmed who leaked the code or where and how it was exfiltrated. GitHub repository has taken it down but already replicated widely, was created by an apparent Future Centred employee, a China-based ODM that manufactures laptops for several OEMs, including Lenovo.