From b897e97c36cb62629a458bc681723ca733404e32 Mon Sep 17 00:00:00 2001
From: Neal Patel <nealpatel@google.com>
Date: Wed, 21 May 2025 14:11:44 -0400
Subject: [PATCH] net/http: strip sensitive proxy headers from redirect
 requests

Similarly to Authentication entries, Proxy-Authentication entries should be stripped to ensure sensitive information is not leaked on redirects outside of the original domain.

https://fetch.spec.whatwg.org/#authentication-entries

Thanks to Takeshi Kaneko (GMO Cybersecurity by Ierae, Inc.) for reporting this issue.

Updates golang/go#73816
Fixes golang/go#73905
Fixes CVE-2025-4673

Change-Id: I1615f31977a2fd014fbc12aae43f82692315a6d0
Reviewed-on: https://go-review.googlesource.com/c/go/+/679255
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>

CVE: CVE-2025-4673

Upstream-Status: Backport [https://github.com/golang/go/commit/b897e97c36cb62629a458bc681723ca733404e32]

Signed-off-by: Praveen Kumar <praveen.kumar@windriver.com>
---
 src/net/http/client.go      | 3 ++-
 src/net/http/client_test.go | 3 +++
 2 files changed, 5 insertions(+), 1 deletion(-)

diff --git a/src/net/http/client.go b/src/net/http/client.go
index 23f4d81..e07616b 100644
--- a/src/net/http/client.go
+++ b/src/net/http/client.go
@@ -805,7 +805,8 @@ func (c *Client) makeHeadersCopier(ireq *Request) func(req *Request, stripSensit
		for k, vv := range ireqhdr {
			sensitive := false
			switch CanonicalHeaderKey(k) {
-			case "Authorization", "Www-Authenticate", "Cookie", "Cookie2":
+			case "Authorization", "Www-Authenticate", "Cookie", "Cookie2",
+				"Proxy-Authorization", "Proxy-Authenticate":
				sensitive = true
			}
			if !(sensitive && stripSensitiveHeaders) {
diff --git a/src/net/http/client_test.go b/src/net/http/client_test.go
index 641d7ff..97150bd 100644
--- a/src/net/http/client_test.go
+++ b/src/net/http/client_test.go
@@ -1541,6 +1541,8 @@ func testClientStripHeadersOnRepeatedRedirect(t *testing.T, mode testMode) {
		if r.Host+r.URL.Path != "a.example.com/" {
			if h := r.Header.Get("Authorization"); h != "" {
				t.Errorf("on request to %v%v, Authorization=%q, want no header", r.Host, r.URL.Path, h)
+			} else if h := r.Header.Get("Proxy-Authorization"); h != "" {
+				t.Errorf("on request to %v%v, Proxy-Authorization=%q, want no header", r.Host, r.URL.Path, h)
			}
		}
		// Follow a chain of redirects from a to b and back to a.
@@ -1569,6 +1571,7 @@ func testClientStripHeadersOnRepeatedRedirect(t *testing.T, mode testMode) {
	req, _ := NewRequest("GET", proto+"://a.example.com/", nil)
	req.Header.Add("Cookie", "foo=bar")
	req.Header.Add("Authorization", "secretpassword")
+	req.Header.Add("Proxy-Authorization", "secretpassword")
	res, err := c.Do(req)
	if err != nil {
		t.Fatal(err)
--
2.40.0
