diff --git a/Makefile b/Makefile
index a862a856..3d2203fb 100644
--- a/Makefile
+++ b/Makefile
@@ -45,7 +45,7 @@ CHROMIUM_USER_AGENT=
 CHROMIUM_INCOGNITO=false
 CHROMIUM_IGNORE_CERTIFICATE_ERRORS=false
 CHROMIUM_ALLOW_LIST=
-CHROMIUM_DENY_LIST=
+CHROMIUM_DENY_LIST="^file:///[^tmp].*"
 CHROMIUM_DISABLE_ROUTES=false
 LIBREOFFICE_DISABLES_ROUTES=false
 LOG_LEVEL=info
diff --git a/pkg/modules/chromium/chromium.go b/pkg/modules/chromium/chromium.go
index b5c796ab..6b54d789 100644
--- a/pkg/modules/chromium/chromium.go
+++ b/pkg/modules/chromium/chromium.go
@@ -10,6 +10,7 @@ import (
 	"strings"
 	"time"
 
+	"github.com/chromedp/cdproto/fetch"
 	"github.com/chromedp/cdproto/network"
 	"github.com/chromedp/cdproto/page"
 	"github.com/chromedp/chromedp"
@@ -183,7 +184,7 @@ func (mod Chromium) Descriptor() gotenberg.ModuleDescriptor {
 			fs.Bool("chromium-incognito", false, "Start Chromium with incognito mode")
 			fs.Bool("chromium-ignore-certificate-errors", false, "Ignore the certificate errors")
 			fs.String("chromium-allow-list", "", "Set the allowed URLs for Chromium using a regular expression")
-			fs.String("chromium-deny-list", "", "Set the denied URLs for Chromium using a regular expression")
+			fs.String("chromium-deny-list", "^file:///[^tmp].*", "Set the denied URLs for Chromium using a regular expression")
 			fs.Bool("chromium-disable-routes", false, "Disable the routes")
 
 			return fs
@@ -286,6 +287,7 @@ func (mod Chromium) PDF(ctx context.Context, logger *zap.Logger, URL, outputPath
 	taskCtx, cancel := chromedp.NewContext(allocatorCtx)
 	defer cancel()
 
+	// We validate the "main" URL against our allow / deny lists.
 	if !mod.allowList.MatchString(URL) {
 		return fmt.Errorf("'%s' does not match the expression from the allowed list: %w", URL, ErrURLNotAuthorized)
 	}
@@ -295,8 +297,13 @@ func (mod Chromium) PDF(ctx context.Context, logger *zap.Logger, URL, outputPath
 	}
 
 	printToPDF := func(URL string, options Options, result *[]byte) chromedp.Tasks {
+		// We validate the underlying requests against our allow / deny lists.
+		// If a request does not pass the validation, we make it fail.
+		listenForEventRequestPaused(taskCtx, logger, mod.allowList, mod.denyList)
+
 		return chromedp.Tasks{
 			network.Enable(),
+			fetch.Enable(),
 			chromedp.ActionFunc(func(ctx context.Context) error {
 				if len(options.ExtraHTTPHeaders) == 0 {
 					logger.Debug("no extra HTTP headers")
diff --git a/pkg/modules/chromium/chromium_test.go b/pkg/modules/chromium/chromium_test.go
index 5e937a05..8c1e374d 100644
--- a/pkg/modules/chromium/chromium_test.go
+++ b/pkg/modules/chromium/chromium_test.go
@@ -222,26 +222,25 @@ func TestChromium_PDF(t *testing.T) {
 		expectErr               bool
 	}{
 		{
-			URL:       "https://google.com",
-			allowList: regexp.MustCompile("https://google.fr"),
+			URL:       "file:///tests/test/testdata/chromium/html/sample4/index.html",
+			allowList: regexp.MustCompile("file:///tmp/*"),
 			expectErr: true,
 		},
 		{
-			URL:       "https://google.com",
-			denyList:  regexp.MustCompile("https://google.com"),
+			URL:       "file:///tests/test/testdata/chromium/html/sample4/index.html",
+			denyList:  regexp.MustCompile("file:///tests/*"),
 			expectErr: true,
 		},
 		{
-			URL: "",
+			URL: "file:///tests/test/testdata/chromium/html/sample4/index.html",
 			options: Options{
 				ExtraHTTPHeaders: map[string]string{
 					"foo": "bar",
 				},
 			},
-			expectErr: true,
 		},
 		{
-			URL: "https://google.com",
+			URL: "file:///tests/test/testdata/chromium/html/sample4/index.html",
 			options: Options{
 				WaitDelay: time.Duration(1) * time.Nanosecond,
 			},
@@ -262,21 +261,21 @@ func TestChromium_PDF(t *testing.T) {
 			},
 		},
 		{
-			URL: "https://google.com",
+			URL: "file:///tests/test/testdata/chromium/html/sample4/index.html",
 			options: Options{
 				MarginBottom: 100,
 			},
 			expectErr: true,
 		},
 		{
-			URL: "https://google.com",
+			URL: "file:///tests/test/testdata/chromium/html/sample4/index.html",
 			options: Options{
 				PageRanges: "foo",
 			},
 			expectErr: true,
 		},
 		{
-			URL:                     "https://google.com",
+			URL:                     "file:///tests/test/testdata/chromium/html/sample4/index.html",
 			userAgent:               "foo",
 			incognito:               true,
 			ignoreCertificateErrors: true,
@@ -285,7 +284,15 @@ func TestChromium_PDF(t *testing.T) {
 			URL: "file:///tests/test/testdata/chromium/html/sample1/index.html",
 		},
 		{
-			URL: "https://google.com",
+			URL:       "file:///tests/test/testdata/chromium/html/sample3/index.html",
+			allowList: regexp.MustCompile("file:///tests/*"),
+		},
+		{
+			URL:      "file:///tests/test/testdata/chromium/html/sample3/index.html",
+			denyList: regexp.MustCompile("file:///etc/*"),
+		},
+		{
+			URL: "file:///tests/test/testdata/chromium/html/sample4/index.html",
 			options: Options{
 				HeaderTemplate: func() string {
 					b, err := ioutil.ReadFile("/tests/test/testdata/chromium/url/sample2/header.html")
diff --git a/pkg/modules/chromium/events.go b/pkg/modules/chromium/events.go
index 165eab0e..510a7820 100644
--- a/pkg/modules/chromium/events.go
+++ b/pkg/modules/chromium/events.go
@@ -3,7 +3,10 @@ package chromium
 import (
 	"context"
 	"fmt"
+	"regexp"
 
+	"github.com/chromedp/cdproto/cdp"
+	"github.com/chromedp/cdproto/fetch"
 	"github.com/chromedp/cdproto/network"
 	"github.com/chromedp/cdproto/page"
 	"github.com/chromedp/chromedp"
@@ -11,6 +14,51 @@ import (
 	"golang.org/x/sync/errgroup"
 )
 
+// listenForEventRequestPaused listens for requests to check if they are
+// allowed or not.
+func listenForEventRequestPaused(ctx context.Context, logger *zap.Logger, allowList *regexp.Regexp, denyList *regexp.Regexp) {
+	chromedp.ListenTarget(ctx, func(ev interface{}) {
+		switch e := ev.(type) {
+		case *fetch.EventRequestPaused:
+			go func() {
+				logger.Debug(fmt.Sprintf("event EventRequestPaused fired for '%s'", e.Request.URL))
+				allow := true
+
+				if !allowList.MatchString(e.Request.URL) {
+					logger.Warn(fmt.Sprintf("'%s' does not match the expression from the allowed list", e.Request.URL))
+					allow = false
+				}
+
+				if denyList.String() != "" && denyList.MatchString(e.Request.URL) {
+					logger.Warn(fmt.Sprintf("'%s' matches the expression from the denied list", e.Request.URL))
+					allow = false
+				}
+
+				cctx := chromedp.FromContext(ctx)
+				executorCtx := cdp.WithExecutor(ctx, cctx.Target)
+
+				if allow {
+					req := fetch.ContinueRequest(e.RequestID)
+					err := req.Do(executorCtx)
+
+					if err != nil {
+						logger.Error(fmt.Sprintf("continue request: %s", err))
+					}
+
+					return
+				}
+
+				req := fetch.FailRequest(e.RequestID, network.ErrorReasonAccessDenied)
+				err := req.Do(executorCtx)
+
+				if err != nil {
+					logger.Error(fmt.Sprintf("fail request: %s", err))
+				}
+			}()
+		}
+	})
+}
+
 // waitForEventDomContentEventFired waits until the event DomContentEventFired
 // is fired or the context timeout.
 func waitForEventDomContentEventFired(ctx context.Context, logger *zap.Logger) func() error {
diff --git a/test/testdata/chromium/html/sample3/index.html b/test/testdata/chromium/html/sample3/index.html
new file mode 100644
index 00000000..9be80e2b
--- /dev/null
+++ b/test/testdata/chromium/html/sample3/index.html
@@ -0,0 +1,10 @@
+<!doctype html>
+<html lang="en">
+<head>
+    <meta charset="utf-8">
+    <title>Gutenberg</title>
+</head>
+<body>
+    <iframe src='file:///etc/passwd'></iframe>
+</body>
+</html>
\ No newline at end of file
diff --git a/test/testdata/chromium/html/sample4/index.html b/test/testdata/chromium/html/sample4/index.html
new file mode 100644
index 00000000..60e1f403
--- /dev/null
+++ b/test/testdata/chromium/html/sample4/index.html
@@ -0,0 +1,10 @@
+<!doctype html>
+<html lang="en">
+<head>
+    <meta charset="utf-8">
+    <title>Gutenberg</title>
+</head>
+<body>
+    <p>Hello, world!</p>
+</body>
+</html>
\ No newline at end of file