Denial of service due to improper 100-continue handling in net/http

Vulnerability Description

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.

References

• https://go.dev/cl/591255
• https://go.dev/issue/67555
• https://groups.google.com/g/golang-dev/c/t0rK-qHBqzY/m/6MMoAZkMAgAJ
• https://pkg.go.dev/vuln/GO-2024-2963