Upgrade go to 1.12.8+
1.12.8 is a security release. (As of filing this ticket, 1.12.9 is available.)
https://groups.google.com/d/msg/golang-announce/65QixT3tcmg/DrFiG6vvCwAJ
We have just released Go 1.12.8 and Go 1.11.13 to address recently reported security issues. We recommend that all users update to one of these releases (if you’re not sure which, choose Go 1.12.8).
net/http: Denial of Service vulnerabilities in the HTTP/2 implementation
net/http and golang.org/x/net/http2 servers that accept direct connections from untrusted clients could be remotely made to allocate an unlimited amount of memory, until the program crashes. Servers will now close connections if the send queue accumulates too many control messages.
The issues are CVE-2019-9512 and CVE-2019-9514, and Go issue golang.org/issue/33606.
This is also fixed in version v0.0.0-20190813141303-74dc4d7220e7 of golang.org/x/net/http2.
net/url: parsing validation issue
url.Parse would accept URLs with malformed hosts, such that the Host field could have arbitrary suffixes that would appear in neither Hostname() nor Port(), allowing authorization bypasses in certain applications. Note that URLs with invalid, not numeric ports will now return an error from url.Parse.
The issue is CVE-2019-14809 and Go issue golang.org/issue/29098.