The various Is methods (IsPrivate, IsLoopback, etc) did not work as expected for IPv4-mapped IPv6 addresses, returning false for addresses which would return true in their traditional IPv4 forms.

A flaw was found in the net package of the Go stdlib. When a malformed DNS message is received as a response to a query, the Lookup functions within the net package can get stuck in an infinite loop. This issue can lead to resource exhaustion and denial of service (DoS) conditions.

The net/http HTTP/1.1 client mishandled the case where a server responds to a request with an "Expect: 100-continue" header with a non-informational (200 or higher) status. This mishandling could leave a client connection in an invalid state, where the next request sent on the connection will fail. An attacker sending a request to a net/http/httputil.ReverseProxy proxy can exploit this mishandling to cause a denial of service by sending "Expect: 100-continue" requests which elicit a non-informational response from the backend. Each such request leaves the proxy with an invalid connection, and causes one subsequent request using that connection to fail.

Processing an incomplete post-handshake message for a QUIC connection can cause a panic.

QUIC connections do not set an upper bound on the amount of data buffered when reading post-handshake messages, allowing a malicious QUIC connection to cause unbounded memory growth. With fix, connections now consistently reject messages larger than 65KiB in size.

A vulnerability was found in Golang FIPS OpenSSL. This flaw allows a malicious user to randomly cause an uninitialized buffer length variable with a zeroed buffer to be returned in FIPS mode. It may also be possible to force a false positive match between non-equal hashes when comparing a trusted computed hmac sum to an untrusted input sum if an attacker can send a zeroed buffer in place of a pre-computed sum.  It is also possible to force a derived key to be all zeros instead of an unpredictable value.  This may have follow-on implications for the Go TLS stack.