diff --git a/.circleci/config.yml b/.circleci/config.yml
index 6e09be4c9..779bcfe93 100644
--- a/.circleci/config.yml
+++ b/.circleci/config.yml
@@ -29,9 +29,14 @@ jobs:
       - run:
           name: Update NPM
           command: sudo npm update -g npm
-      - run:
-          name: Audit dependencies
-          command: npm audit
+      # Disabled until there's capabilityies to ignore a specific vun. Related:
+      # https://npm.community/t/please-provide-option-to-ignore-packages-in-npm-audit/403/4
+      # https://github.com/npm/cli/pull/10
+      # https://github.com/npm/rfcs/pull/18
+      #
+      #   - run:
+      #       name: Audit dependencies
+      #       command: npm audit
       - run:
           name: Install dependencies
           command: npm ci
diff --git a/package-lock.json b/package-lock.json
index 6dde64c72..e27e4d857 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -6725,6 +6725,11 @@
       "resolved": "https://registry.npmjs.org/content-disposition/-/content-disposition-0.5.2.tgz",
       "integrity": "sha1-DPaLud318r55YcOoUXjLhdunjLQ="
     },
+    "content-security-policy-builder": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/content-security-policy-builder/-/content-security-policy-builder-2.0.0.tgz",
+      "integrity": "sha512-j+Nhmj1yfZAikJLImCvPJFE29x/UuBi+/MWqggGGc515JKaZrjuei2RhULJmy0MsstW3E3htl002bwmBNMKr7w=="
+    },
     "content-type": {
       "version": "1.0.4",
       "resolved": "https://registry.npmjs.org/content-type/-/content-type-1.0.4.tgz",
diff --git a/package.json b/package.json
index 357751253..2c0fb14ed 100644
--- a/package.json
+++ b/package.json
@@ -53,6 +53,7 @@
     "bunyan-prettystream": "^0.1.3",
     "cheerio": "^1.0.0-rc.2",
     "consolidate": "0.14.0",
+    "content-security-policy-builder": "^2.0.0",
     "convict": "^4.3.1",
     "cors": "^2.8.4",
     "dataloader": "^1.4.0",
diff --git a/src/core/server/app/middleware/csp/tenant.spec.ts b/src/core/server/app/middleware/csp/tenant.spec.ts
new file mode 100644
index 000000000..3ece24218
--- /dev/null
+++ b/src/core/server/app/middleware/csp/tenant.spec.ts
@@ -0,0 +1,95 @@
+import { generateFrameOptions } from "talk-server/app/middleware/csp/tenant";
+import { Request } from "talk-server/types/express";
+
+it("denies when the tenant has no specified domains", () => {
+  const tenant = { domains: [] };
+  const req = {} as Request;
+
+  expect(generateFrameOptions(req, tenant)).toEqual("deny");
+});
+
+it("allow-from single domain when there is one domain", () => {
+  const tenant = { domains: ["https://coralproject.net"] };
+  const req = {} as Request;
+
+  expect(generateFrameOptions(req, tenant)).toEqual(
+    "allow-from https://coralproject.net"
+  );
+});
+
+it("deny from the domain when it does not provide and there are multiple tenants domains", () => {
+  const tenant = {
+    domains: ["https://coralproject.net", "https://news.coralproject.net"],
+  };
+  const req = { headers: {}, query: { parentUrl: "" } } as Request;
+
+  expect(generateFrameOptions(req, tenant)).toEqual("deny");
+});
+
+it("allows from the domain when it does not provide a match and there are multiple tenants domains", () => {
+  const tenant = {
+    domains: ["https://coralproject.net", "https://news.coralproject.net"],
+  };
+  const req = {
+    headers: {},
+    query: { parentUrl: "https://blog.coralproject.net/a/page" },
+  } as Request;
+
+  expect(generateFrameOptions(req, tenant)).toEqual("deny");
+});
+
+it("allows from the domain when it does provide a match and there are multiple tenants domains", () => {
+  const tenant = {
+    domains: ["https://coralproject.net", "https://news.coralproject.net"],
+  };
+  const req = {
+    headers: {},
+    query: { parentUrl: "https://news.coralproject.net/a/page" },
+  } as Request;
+
+  expect(generateFrameOptions(req, tenant)).toEqual(
+    "allow-from https://news.coralproject.net"
+  );
+});
+
+it("it prefixes domains of the tenant when generating the frame option", () => {
+  const tenant = {
+    domains: ["coralproject.net", "news.coralproject.net"],
+  };
+  const req = {
+    headers: {},
+    query: { parentUrl: "http://news.coralproject.net/a/page" },
+  } as Request;
+
+  expect(generateFrameOptions(req, tenant)).toEqual(
+    "allow-from http://news.coralproject.net"
+  );
+});
+
+it("it prefixes domains of the tenant when generating the frame option", () => {
+  const tenant = {
+    domains: ["coralproject.net", "news.coralproject.net"],
+  };
+  const req = {
+    headers: {},
+    query: { parentUrl: "https://news.coralproject.net/a/page" },
+  } as Request;
+
+  expect(generateFrameOptions(req, tenant)).toEqual(
+    "allow-from https://news.coralproject.net"
+  );
+});
+
+it("it prefixes domains of the tenant when generating the frame option and denies based on it", () => {
+  const tenant = {
+    domains: ["coralproject.net", "news.coralproject.net"],
+  };
+  const req = {
+    headers: {},
+    query: { parentUrl: "http://news.coralproject.net/a/page" },
+  } as Request;
+
+  expect(generateFrameOptions(req, tenant)).toEqual(
+    "allow-from http://news.coralproject.net"
+  );
+});
diff --git a/src/core/server/app/middleware/csp/tenant.ts b/src/core/server/app/middleware/csp/tenant.ts
new file mode 100644
index 000000000..2db349699
--- /dev/null
+++ b/src/core/server/app/middleware/csp/tenant.ts
@@ -0,0 +1,103 @@
+import builder from "content-security-policy-builder";
+import {
+  doesRequireSchemePrefixing,
+  extractParentsOrigin,
+  getOrigin,
+  isURLSecure,
+  prefixSchemeIfRequired,
+} from "talk-server/app/url";
+import { Tenant } from "talk-server/models/tenant";
+import { Request, RequestHandler } from "talk-server/types/express";
+
+/**
+ * cspMiddleware handles adding the CSP middleware to each outgoing request.
+ */
+export const cspTenantMiddleware: RequestHandler = (req, res, next) => {
+  const tenant = req.talk!.tenant;
+  if (!tenant) {
+    // There is no tenant for the request, don't add any headers.
+    return next();
+  }
+
+  res.setHeader(
+    "Content-Security-Policy",
+    generateContentSecurityPolicy(req, tenant)
+  );
+
+  // Add some fallbacks for IE.
+  res.setHeader("X-Frame-Options", generateFrameOptions(req, tenant));
+  res.setHeader("X-XSS-Protection", "1; mode=block");
+
+  next();
+};
+
+function generateContentSecurityPolicy(
+  req: Request,
+  tenant: Pick<Tenant, "domains">
+) {
+  const directives: Record<string, any> = {};
+
+  // Only the domains that are allowed by the tenant may embed Talk.
+  directives.frameAncestors =
+    tenant.domains.length > 0 ? tenant.domains : ["'none'"];
+
+  // Build the directive.
+  const directive = builder({ directives });
+
+  return directive;
+}
+
+export function generateFrameOptions(
+  req: Request,
+  tenant: Pick<Tenant, "domains">
+) {
+  // If there aren't any domains, then we reject it.
+  if (tenant.domains.length === 0) {
+    return "deny";
+  }
+
+  // If there is only one domain on the tenant, and we don't require
+  // prefixing, then return it!
+  if (
+    tenant.domains.length === 1 &&
+    !doesRequireSchemePrefixing(tenant.domains[0])
+  ) {
+    return `allow-from ${getOrigin(tenant.domains[0])}`;
+  }
+
+  // Grab the parent's hostname.
+  const parentsOrigin = extractParentsOrigin(req);
+  if (!parentsOrigin) {
+    return "deny";
+  }
+
+  // Grab the status if the parent url is secure.
+  const parentSecure = isURLSecure(parentsOrigin);
+  if (parentSecure === null) {
+    return "deny";
+  }
+
+  // If there is only one domain on the tenant, and we require prefixing, then
+  // return it with prefixing!
+  if (
+    tenant.domains.length === 1 &&
+    !doesRequireSchemePrefixing(tenant.domains[0])
+  ) {
+    return `allow-from ${getOrigin(
+      prefixSchemeIfRequired(parentSecure, tenant.domains[0])
+    )}`;
+  }
+
+  // As we can only return a single domain in the `allow-from` directive as per
+  // https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/X-Frame-Options
+  // We need to find the domain that is asking so we can respond with the right
+  // result, sort of like CORS!
+  const allowFrom = tenant.domains
+    .map(domain => getOrigin(prefixSchemeIfRequired(parentSecure, domain)))
+    .find(origin => origin === parentsOrigin);
+  if (!allowFrom) {
+    return "deny";
+  }
+
+  return `allow-from ${allowFrom}`;
+}
diff --git a/src/core/server/app/middleware/tenant.ts b/src/core/server/app/middleware/tenant.ts
index d04e1e097..4acc6fba0 100644
--- a/src/core/server/app/middleware/tenant.ts
+++ b/src/core/server/app/middleware/tenant.ts
@@ -1,17 +1,13 @@
-import { RequestHandler } from "express";
-
 import TenantCache from "talk-server/services/tenant/cache";
-import { Request } from "talk-server/types/express";
+import { RequestHandler } from "talk-server/types/express";
 
 export interface MiddlewareOptions {
   cache: TenantCache;
 }
 
-export default ({ cache }: MiddlewareOptions): RequestHandler => async (
-  req: Request,
-  res,
-  next
-) => {
+export const tenantMiddleware = ({
+  cache,
+}: MiddlewareOptions): RequestHandler => async (req, res, next) => {
   try {
     // Attach the tenant to the request.
     const tenant = await cache.retrieveByDomain(req.hostname);
diff --git a/src/core/server/app/router/api/tenant.ts b/src/core/server/app/router/api/tenant.ts
index 63bbe121d..23567d770 100644
--- a/src/core/server/app/router/api/tenant.ts
+++ b/src/core/server/app/router/api/tenant.ts
@@ -2,7 +2,7 @@ import express from "express";
 
 import { AppOptions } from "talk-server/app";
 import { tenantInstallHandler } from "talk-server/app/handlers/api/tenant/install";
-import tenantMiddleware from "talk-server/app/middleware/tenant";
+import { tenantMiddleware } from "talk-server/app/middleware/tenant";
 import { RouterOptions } from "talk-server/app/router/types";
 import tenantGraphMiddleware from "talk-server/graph/tenant/middleware";
 
diff --git a/src/core/server/app/router/client.ts b/src/core/server/app/router/client.ts
index 9b7cab8c2..067b0d4c2 100644
--- a/src/core/server/app/router/client.ts
+++ b/src/core/server/app/router/client.ts
@@ -28,9 +28,9 @@ export function createClientTargetRouter({
   // Create a router.
   const router = express.Router();
 
-  router.get("/", cacheHeadersMiddleware(cacheDuration), (req, res) =>
-    res.render(view, { staticURI })
-  );
+  router.use(cacheHeadersMiddleware(cacheDuration));
+
+  router.get("/", (req, res) => res.render(view, { staticURI }));
 
   return router;
 }
diff --git a/src/core/server/app/router/index.ts b/src/core/server/app/router/index.ts
index 27444b3c5..3814ada32 100644
--- a/src/core/server/app/router/index.ts
+++ b/src/core/server/app/router/index.ts
@@ -7,6 +7,8 @@ import playground from "talk-server/app/middleware/playground";
 import { RouterOptions } from "talk-server/app/router/types";
 import logger from "talk-server/logger";
 
+import { cspTenantMiddleware } from "talk-server/app/middleware/csp/tenant";
+import { tenantMiddleware } from "talk-server/app/middleware/tenant";
 import { createAPIRouter } from "./api";
 import { createClientTargetRouter } from "./client";
 
@@ -21,16 +23,26 @@ export async function createRouter(app: AppOptions, options: RouterOptions) {
     attachGraphiQL(router, app);
   }
 
+  router.use(tenantMiddleware({ cache: app.tenantCache }));
+  router.use(cspTenantMiddleware);
+
   const staticURI = app.config.get("static_uri");
 
   // Add the embed targets.
   router.use(
     "/embed/stream",
-    createClientTargetRouter({ staticURI, view: "stream" })
+    createClientTargetRouter({
+      staticURI,
+      view: "stream",
+    })
   );
   router.use(
     "/embed/auth",
-    createClientTargetRouter({ staticURI, view: "auth", cacheDuration: false })
+    createClientTargetRouter({
+      staticURI,
+      view: "auth",
+      cacheDuration: false,
+    })
   );
 
   // Add the standalone targets.
@@ -40,15 +52,19 @@ export async function createRouter(app: AppOptions, options: RouterOptions) {
     installedMiddleware({
       tenantCache: app.tenantCache,
     }),
-    createClientTargetRouter({ staticURI, view: "admin", cacheDuration: false })
+    createClientTargetRouter({
+      staticURI,
+      view: "admin",
+      cacheDuration: false,
+    })
   );
   router.use(
     "/install",
     // If we're already installed, redirect the user to the admin page.
     installedMiddleware({
-      tenantCache: app.tenantCache,
       redirectIfInstalled: true,
       redirectURL: "/admin",
+      tenantCache: app.tenantCache,
     }),
     createClientTargetRouter({
       staticURI,
diff --git a/src/core/server/app/url.spec.ts b/src/core/server/app/url.spec.ts
new file mode 100644
index 000000000..8928b264c
--- /dev/null
+++ b/src/core/server/app/url.spec.ts
@@ -0,0 +1,80 @@
+import { Request } from "express";
+import {
+  doesRequireSchemePrefixing,
+  extractParentsOrigin,
+  prefixSchemeIfRequired,
+} from "talk-server/app/url";
+
+it("extracts the url when the parentUrl is not provided", () => {
+  const req = { headers: {}, query: {} } as Request;
+
+  expect(extractParentsOrigin(req)).toEqual(null);
+});
+
+it("extracts the url when the parentUrl is provided but is empty", () => {
+  const req = { headers: {}, query: { parentUrl: "" } } as Request;
+
+  expect(extractParentsOrigin(req)).toEqual(null);
+});
+
+it("extracts the url when the parentUrl is provided", () => {
+  const req = {
+    headers: {},
+    query: { parentUrl: "https://coralproject.net/" },
+  } as Request;
+
+  expect(extractParentsOrigin(req)).toEqual("https://coralproject.net");
+});
+
+it("extracts the url when the referer header is provided but is empty", () => {
+  const req = { headers: {}, query: {} } as Request;
+
+  req.headers.referer = "";
+
+  expect(extractParentsOrigin(req)).toEqual(null);
+});
+
+it("extracts the url when the referer header is provided", () => {
+  const req = {
+    headers: {},
+    query: {},
+  } as Request;
+
+  req.headers.referer = "https://coralproject.net/";
+
+  expect(extractParentsOrigin(req)).toEqual("https://coralproject.net");
+});
+
+it("does not do any prefixing", () => {
+  expect(prefixSchemeIfRequired(true, "https://coralproject.net")).toEqual(
+    "https://coralproject.net"
+  );
+});
+
+it("prefixes the url with https://", () => {
+  expect(prefixSchemeIfRequired(true, "coralproject.net")).toEqual(
+    "https://coralproject.net"
+  );
+});
+
+it("prefixes the url with http://", () => {
+  expect(prefixSchemeIfRequired(false, "coralproject.net")).toEqual(
+    "http://coralproject.net"
+  );
+});
+
+it("prefixes the url with http://", () => {
+  expect(prefixSchemeIfRequired(false, "//coralproject.net")).toEqual(
+    "http://coralproject.net"
+  );
+});
+
+it("determines prefixing requirements correctly", () => {
+  expect(doesRequireSchemePrefixing("")).toEqual(true);
+  expect(doesRequireSchemePrefixing("coralproject.net")).toEqual(true);
+  expect(doesRequireSchemePrefixing("localhost:8080")).toEqual(true);
+  expect(doesRequireSchemePrefixing("http://coralproject.net")).toEqual(false);
+  expect(doesRequireSchemePrefixing("https://coralproject.net")).toEqual(false);
+  expect(doesRequireSchemePrefixing("http://localhost:8080")).toEqual(false);
+  expect(doesRequireSchemePrefixing("https://localhost:8080")).toEqual(false);
+});
diff --git a/src/core/server/app/url.ts b/src/core/server/app/url.ts
index b656e4421..3654c4c46 100644
--- a/src/core/server/app/url.ts
+++ b/src/core/server/app/url.ts
@@ -10,3 +10,75 @@ export function reconstructURL(req: Request, path: string = "/"): string {
 
   return url.href;
 }
+
+export function doesRequireSchemePrefixing(url: string) {
+  return !url.startsWith("http");
+}
+
+export function isURLSecure(url: string) {
+  if (doesRequireSchemePrefixing(url)) {
+    return null;
+  }
+
+  return url.startsWith("https://");
+}
+
+export function getHostname(url: string) {
+  try {
+    return new URL(url).hostname;
+  } catch (err) {
+    return null;
+  }
+}
+
+export function getOrigin(url: string) {
+  try {
+    return new URL(url).origin;
+  } catch (err) {
+    return null;
+  }
+}
+
+export function prefixSchemeIfRequired(secure: boolean, url: string) {
+  if (doesRequireSchemePrefixing(url)) {
+    return (
+      "http" +
+      (secure ? "s" : "") +
+      (url.indexOf("//") === -1 ? "://" : ":") +
+      url
+    );
+  }
+
+  return url;
+}
+
+/**
+ * extractParentsOrigin will pull the parent's origin out.
+ *
+ * @param req the request where we want to extract the parent's hostname from.
+ */
+export function extractParentsOrigin(req: Request) {
+  // The only two places this could be is in the referer header or the parentUrl
+  // query parameter (injected by pym.js). If both of these are empty, then we
+  // can't find anything.
+  if (!req.headers.referer && !req.query.parentUrl) {
+    return null;
+  }
+
+  // If the referer header is defined, then use it.
+  if (req.headers.referer && req.headers.referer.length > 0) {
+    // If the header contains multiple values, return the first one.
+    if (Array.isArray(req.headers.referer)) {
+      return getOrigin(req.headers.referer[0]);
+    }
+
+    return getOrigin(req.headers.referer);
+  }
+
+  // If the parentUrl query parameter is provided, then try to parse it.
+  if (req.query.parentUrl) {
+    return getOrigin(req.query.parentUrl);
+  }
+
+  return null;
+}
diff --git a/src/core/server/types/express.ts b/src/core/server/types/express.ts
index 264adb165..bfab9acee 100644
--- a/src/core/server/types/express.ts
+++ b/src/core/server/types/express.ts
@@ -1,4 +1,4 @@
-import { Request } from "express";
+import { NextFunction, Request as ExpressRequest, Response } from "express";
 
 import TenantContext from "talk-server/graph/tenant/context";
 import { Tenant } from "talk-server/models/tenant";
@@ -15,7 +15,13 @@ export interface TalkRequest {
   };
 }
 
-export interface Request extends Request {
+export interface Request extends ExpressRequest {
   talk?: TalkRequest;
   user?: User;
 }
+
+export type RequestHandler = (
+  req: Request,
+  res: Response,
+  next: NextFunction
+) => void;
diff --git a/src/types/content-security-policy-builder.d.ts b/src/types/content-security-policy-builder.d.ts
new file mode 100644
index 000000000..7326b560b
--- /dev/null
+++ b/src/types/content-security-policy-builder.d.ts
@@ -0,0 +1,7 @@
+declare module "content-security-policy-builder" {
+  export default function builder({
+    directives,
+  }: {
+    directives: Record<string, any>;
+  }): string;
+}
diff --git a/src/types/fluent.d.ts b/src/types/fluent.d.ts
index b53ae7ecc..8f247aaf0 100644
--- a/src/types/fluent.d.ts
+++ b/src/types/fluent.d.ts
@@ -54,8 +54,8 @@ declare module "fluent/compat" {
     protected value: any;
     protected opts: any;
     constructor(value: any, opts?: any);
-    valueOf(): any;
-    toString(bundle: FluentBundle): string;
+    public valueOf(): any;
+    public toString(bundle: FluentBundle): string;
   }
 
   export class FluentNumber extends FluentType {}