diff --git a/front_end/sdk/Cookie.js b/front_end/sdk/Cookie.js
index 9051a129df..796171e43e 100644
--- a/front_end/sdk/Cookie.js
+++ b/front_end/sdk/Cookie.js
@@ -219,6 +219,57 @@ export class Cookie {
   getCookieLine() {
     return this._cookieLine;
   }
+
+  /**
+   * @param {string} securityOrigin
+   * @returns {boolean}
+   */
+  matchesSecurityOrigin(securityOrigin) {
+    const hostname = new URL(securityOrigin).hostname;
+    return Cookie.isDomainMatch(this.domain(), hostname);
+  }
+
+  /**
+   * @param {string} domain
+   * @param {string} hostname
+   * @returns {boolean}
+   */
+  static isDomainMatch(domain, hostname) {
+    // This implementation mirrors
+    // https://source.chromium.org/search?q=net::cookie_util::IsDomainMatch()
+    //
+    // Can domain match in two ways; as a domain cookie (where the cookie
+    // domain begins with ".") or as a host cookie (where it doesn't).
+
+    // Some consumers of the CookieMonster expect to set cookies on
+    // URLs like http://.strange.url.  To retrieve cookies in this instance,
+    // we allow matching as a host cookie even when the domain_ starts with
+    // a period.
+    if (hostname === domain) {
+      return true;
+    }
+
+    // Domain cookie must have an initial ".".  To match, it must be
+    // equal to url's host with initial period removed, or a suffix of
+    // it.
+
+    // Arguably this should only apply to "http" or "https" cookies, but
+    // extension cookie tests currently use the funtionality, and if we
+    // ever decide to implement that it should be done by preventing
+    // such cookies from being set.
+    if (!domain || domain[0] !== '.') {
+      return false;
+    }
+
+    // The host with a "." prefixed.
+    if (domain.substr(1) === hostname) {
+      return true;
+    }
+
+    // A pure suffix of the host (ok since we know the domain already
+    // starts with a ".")
+    return hostname.length > domain.length && hostname.endsWith(domain);
+  }
 }
 
 /**
diff --git a/front_end/sdk/CookieModel.js b/front_end/sdk/CookieModel.js
index c3c1b0b9cf..e10e031d9b 100644
--- a/front_end/sdk/CookieModel.js
+++ b/front_end/sdk/CookieModel.js
@@ -69,7 +69,7 @@ export class CookieModel extends SDKModel {
     const cookies = await this.getCookiesForDomain(domain || null);
     if (securityOrigin) {
       const cookiesToDelete = cookies.filter(cookie => {
-        return securityOrigin.endsWith(cookie.domain());
+        return cookie.matchesSecurityOrigin(securityOrigin);
       });
       await this.deleteCookies(cookiesToDelete);
     } else {
diff --git a/test/e2e/application/storage_test.ts b/test/e2e/application/storage_test.ts
index 98fa18e111..76140fff43 100644
--- a/test/e2e/application/storage_test.ts
+++ b/test/e2e/application/storage_test.ts
@@ -38,7 +38,6 @@ describe('The Application Tab', async () => {
       return data.length ? data : undefined;
     });
 
-
     assert.sameDeepMembers(dataGridRowValuesBefore, [
       {
         name: 'third_party',
diff --git a/test/e2e/resources/application/cross-origin-cookies.html b/test/e2e/resources/application/cross-origin-cookies.html
index fcecf2eb79..adf40ad47c 100644
--- a/test/e2e/resources/application/cross-origin-cookies.html
+++ b/test/e2e/resources/application/cross-origin-cookies.html
@@ -7,6 +7,7 @@
   document.cookie = 'foo=bar;path=/';
   document.cookie = 'foo2=bar;path=/';
 
+  // Load cross origin resource by switching the hostname to 127.0.0.1
   const url = new URL('./set-cookies.rawresponse', document.location);
   const image = new Image();
   image.src = url.toString().replace('localhost', '127.0.0.1');
diff --git a/test/e2e/resources/recorder/oop-iframe.html b/test/e2e/resources/recorder/oop-iframe.html
new file mode 100644
index 0000000000..5333b46c02
--- /dev/null
+++ b/test/e2e/resources/recorder/oop-iframe.html
@@ -0,0 +1,7 @@
+<!--
+  Copyright 2021 The Chromium Authors. All rights reserved.
+  Use of this source code is governed by a BSD-style license that can be
+  found in the LICENSE file.
+-->
+<h1>OOP iframe</h1>
+<button>Button in OOP iframe</button>
diff --git a/test/unittests/front_end/sdk/Cookie_test.ts b/test/unittests/front_end/sdk/Cookie_test.ts
index 5edc6ef792..a39497ee90 100644
--- a/test/unittests/front_end/sdk/Cookie_test.ts
+++ b/test/unittests/front_end/sdk/Cookie_test.ts
@@ -174,4 +174,19 @@ describeWithEnvironment('Cookie', () => {
     assertNotNull(expiresDate);
     assert.strictEqual(expiresDate.toISOString(), new Date(expires).toISOString());
   });
+
+  it('can check if a cookie domain matches a given host', () => {
+    assert.isTrue(SDK.Cookie.Cookie.isDomainMatch('example.com', 'example.com'));
+    assert.isFalse(SDK.Cookie.Cookie.isDomainMatch('www.example.com', 'example.com'));
+
+    assert.isTrue(SDK.Cookie.Cookie.isDomainMatch('.example.com', 'example.com'));
+    assert.isTrue(SDK.Cookie.Cookie.isDomainMatch('.example.com', 'www.example.com'));
+    assert.isFalse(SDK.Cookie.Cookie.isDomainMatch('.www.example.com', 'example.com'));
+
+    assert.isFalse(SDK.Cookie.Cookie.isDomainMatch('example.com', 'example.de'));
+    assert.isFalse(SDK.Cookie.Cookie.isDomainMatch('.example.com', 'example.de'));
+    assert.isFalse(SDK.Cookie.Cookie.isDomainMatch('.example.de', 'example.de.vu'));
+
+    assert.isFalse(SDK.Cookie.Cookie.isDomainMatch('example.com', 'notexample.com'));
+  });
 });