diff --git a/static/partials/pdfcanvas_sandbox.html b/static/partials/pdfcanvas_sandbox.html
index dc20166e..3750d8e3 100644
--- a/static/partials/pdfcanvas_sandbox.html
+++ b/static/partials/pdfcanvas_sandbox.html
@@ -2,6 +2,7 @@
 <html>
 	<head>
 		<title>pdf.js Sandbox</title>
+		<meta http-equiv="Content-Security-Policy" content="default-src 'none'; script-src __PARENT_ORIGIN__; img-src 'self'; style-src 'unsafe-inline'">
 		<style type="text/css">
 		html, body {
 			height:100%;
