This vulnerability is currently awaiting analysis.
The OpenSSL ECDSA signature algorithm has been shown to be vulnerable to a timing side channel attack. An attacker could use variations in the signing algorithm to recover the private key. Fixed in OpenSSL 1.1.0j-dev (Affected 1.1.0-1.1.0i). Fixed in OpenSSL 1.1.1a-dev (Affected 1.1.1).