Sensitive headers incorrectly sent after cross-domain redirect in net/http

Vulnerability Description

The HTTP client drops sensitive headers after following a cross-domain redirect. For example, a request to a.com/ containing an Authorization header which is redirected to b.com/ will not send that header to b.com. In the event that the client received a subsequent same-domain redirect, however, the sensitive headers would be restored. For example, a chain of redirects from a.com/, to b.com/1, and finally to b.com/2 would incorrectly send the Authorization header to b.com/2.

References

• https://go.dev/cl/643100
• https://go.dev/issue/70530
• https://groups.google.com/g/golang-dev/c/CAWXhan3Jww/m/bk9LAa-lCgAJ
• https://groups.google.com/g/golang-dev/c/bG8cv1muIBM/m/G461hA6lCgAJ
• https://pkg.go.dev/vuln/GO-2025-3420