From bcb1b7ea2575b140f7bf202ad4f779e402cd6094 Mon Sep 17 00:00:00 2001
From: SkyZeroZx <73321943+SkyZeroZx@users.noreply.github.com>
Date: Thu, 4 Jun 2026 22:37:21 -0500
Subject: [PATCH] fix(http): preserve empty referrer option in HttpRequest

Preserve `referrer: ''` when constructing and cloning HttpRequest.

An empty string is a valid Fetch referrer value and is documented by
Angular as the way to omit referrer information for sensitive requests.
The previous truthy checks treated it as if the option was not provided,
causing requests to fall back to the browser default referrer behavior.

(cherry picked from commit 1e54b8f5ecd2bf0cf863311ed2bbe13ffe3f17b8)
---
 packages/common/http/src/request.ts       |  5 +++--
 packages/common/http/test/request_spec.ts | 11 +++++++++++
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/packages/common/http/src/request.ts b/packages/common/http/src/request.ts
index 8bcc1bd13a4..8aa947007c0 100644
--- a/packages/common/http/src/request.ts
+++ b/packages/common/http/src/request.ts
@@ -523,7 +523,7 @@ export class HttpRequest<T> {
         this.integrity = options.integrity;
       }
 
-      if (options.referrer) {
+      if (options.referrer !== undefined) {
         this.referrer = options.referrer;
       }
 
@@ -734,7 +734,8 @@ export class HttpRequest<T> {
     const mode = update.mode || this.mode;
     const redirect = update.redirect || this.redirect;
     const credentials = update.credentials || this.credentials;
-    const referrer = update.referrer || this.referrer;
+
+    const referrer = update.referrer ?? this.referrer;
     const integrity = update.integrity || this.integrity;
     const referrerPolicy = update.referrerPolicy || this.referrerPolicy;
     // Carefully handle the transferCache to differentiate between
diff --git a/packages/common/http/test/request_spec.ts b/packages/common/http/test/request_spec.ts
index 44904e6f711..194008ed27a 100644
--- a/packages/common/http/test/request_spec.ts
+++ b/packages/common/http/test/request_spec.ts
@@ -95,6 +95,10 @@ describe('HttpRequest', () => {
       const req = new HttpRequest('GET', '/test', {referrer: 'about:client'});
       expect(req.referrer).toBe('about:client');
     });
+    it('should preserve an empty string referrer (used to suppress the Referer header)', () => {
+      const req = new HttpRequest('GET', '/test', {referrer: ''});
+      expect(req.referrer).toBe('');
+    });
     it('should allow setting referrerPolicy option', () => {
       const req = new HttpRequest('GET', '/test', {referrerPolicy: 'no-referrer'});
       expect(req.referrerPolicy).toBe('no-referrer');
@@ -175,6 +179,13 @@ describe('HttpRequest', () => {
     it('and updates the referrer', () => {
       expect(req.clone({referrer: 'https://example.com'}).referrer).toBe('https://example.com');
     });
+    it('and preserves an existing empty string referrer when the update omits it', () => {
+      const emptyReferrerReq = new HttpRequest('GET', '/test', {referrer: ''});
+      expect(emptyReferrerReq.clone().referrer).toBe('');
+    });
+    it('and can update the referrer to an empty string', () => {
+      expect(req.clone({referrer: ''}).referrer).toBe('');
+    });
     it('and updates the integrity', () => {
       expect(req.clone({integrity: 'sha512-...'}).integrity).toBe('sha512-...');
     });