CVE-2021-34558: Input Validation

crypto/tls clients can panic when provided a certificate of the wrong type for the negotiated parameters. net/http clients performing HTTPS requests are also affected. The panic can be triggered by an attacker in a privileged network position without access to the server certificate's private key, as long as a trusted ECDSA or Ed25519 certificate for the server exists (or can be issued), or the client is configured with Config.InsecureSkipVerify. Clients that disable all TLSRSA cipher suites (that is, TLS 1.0–1.2 cipher suites without ECDHE), as well as TLS 1.3-only clients, are unaffected.

References: https://golang.org/doc/devel/release https://github.com/golang/go/issues/47145 https://github.com/golang/go/issues/47144

— Red Hat

Golang Go is vulnerable to a denial of service, caused by the failure to properly assert that the type of public key in an X.509 certificate matches the expected type in the crypto/tls package. By persuading a victim to connect to a specially-crafted TLS server, a remote attacker could exploit this vulnerability to cause a TLS client to panic.

— IBM

The crypto/tls package of Go through 1.16.5 does not properly assert that the type of public key in an X.509 certificate matches the expected type when doing a RSA based key exchange, allowing a malicious TLS server to cause a TLS client to panic.