diff --git a/addons/im_livechat/static/src/legacy/public_livechat.js b/addons/im_livechat/static/src/legacy/public_livechat.js
index 46db2d8cd81..8a714e99cd2 100644
--- a/addons/im_livechat/static/src/legacy/public_livechat.js
+++ b/addons/im_livechat/static/src/legacy/public_livechat.js
@@ -3530,6 +3530,7 @@ odoo.define('im_livechat.legacy.mail.DocumentViewer', function (require) {
 
 var core = require('web.core');
 var Widget = require('web.Widget');
+var { hidePDFJSButtons } = require('@web/js/libs/pdfjs');
 
 var QWeb = core.qweb;
 
@@ -3658,6 +3659,9 @@ var DocumentViewer = Widget.extend({
         this.$('.o_viewer_content').html(QWeb.render('im_livechat.legacy.mail.DocumentViewer.Content', {
             widget: this
         }));
+        if (this.activeAttachment.fileType === 'application/pdf') {
+            hidePDFJSButtons(this.$('.o_viewer_content')[0]);
+        }
         this.$('.o_viewer_img').on("load", _.bind(this._onImageLoaded, this));
         this.$('[data-toggle="tooltip"]').tooltip({ delay: 0 });
         this._reset();
diff --git a/addons/mail/static/src/components/attachment_viewer/attachment_viewer.js b/addons/mail/static/src/components/attachment_viewer/attachment_viewer.js
index bd2f3896c73..108006b14d3 100644
--- a/addons/mail/static/src/components/attachment_viewer/attachment_viewer.js
+++ b/addons/mail/static/src/components/attachment_viewer/attachment_viewer.js
@@ -5,6 +5,8 @@ import useShouldUpdateBasedOnProps from '@mail/component_hooks/use_should_update
 import useStore from '@mail/component_hooks/use_store/use_store';
 import { link } from '@mail/model/model_field_command';
 
+import { hidePDFJSButtons } from '@web/js/libs/pdfjs';
+
 const { Component, QWeb } = owl;
 const { useRef } = owl.hooks;
 
@@ -53,6 +55,10 @@ class AttachmentViewer extends Component {
          * transformation on image visualisation.
          */
         this._zoomerRef = useRef('zoomer');
+        /**
+         * Reference of the IFRAME node when the attachment is a PDF.
+         */
+        this._iframeViewerPdfRef = useRef('iframeViewerPdf');
         /**
          * Tracked translate transformations on image visualisation. This is
          * not observed with `useStore` because they are used to compute zoomer
@@ -67,6 +73,7 @@ class AttachmentViewer extends Component {
     mounted() {
         this.el.focus();
         this._handleImageLoad();
+        this._hideUnwantedPdfJsButtons();
         document.addEventListener('click', this._onClickGlobal);
     }
 
@@ -75,6 +82,7 @@ class AttachmentViewer extends Component {
      */
     patched() {
         this._handleImageLoad();
+        this._hideUnwantedPdfJsButtons();
     }
 
     willUnmount() {
@@ -169,6 +177,17 @@ class AttachmentViewer extends Component {
         }
     }
 
+    /**
+     * @see 'hidePDFJSButtons'
+     *
+     * @private
+     */
+    _hideUnwantedPdfJsButtons() {
+        if (this._iframeViewerPdfRef.el) {
+            hidePDFJSButtons(this._iframeViewerPdfRef.el);
+        }
+    }
+
     /**
      * Display the previous attachment in the list of attachments.
      *
diff --git a/addons/mail/static/src/components/attachment_viewer/attachment_viewer.xml b/addons/mail/static/src/components/attachment_viewer/attachment_viewer.xml
index af0651291d9..e3c5ef1f312 100644
--- a/addons/mail/static/src/components/attachment_viewer/attachment_viewer.xml
+++ b/addons/mail/static/src/components/attachment_viewer/attachment_viewer.xml
@@ -46,7 +46,7 @@
                     </div>
                 </t>
                 <t t-if="attachmentViewer.attachment.fileType === 'application/pdf'">
-                    <iframe class="o_AttachmentViewer_view o_AttachmentViewer_viewIframe o_AttachmentViewer_viewPdf" t-att-class="{ 'o-isMobile': env.messaging.device.isMobile }" t-att-src="attachmentViewer.attachment.defaultSource"/>
+                    <iframe class="o_AttachmentViewer_view o_AttachmentViewer_viewIframe o_AttachmentViewer_viewPdf" t-ref="iframeViewerPdf" t-att-class="{ 'o-isMobile': env.messaging.device.isMobile }" t-att-src="attachmentViewer.attachment.defaultSource"/>
                 </t>
                 <t t-if="attachmentViewer.attachment.isTextFile">
                     <iframe class="o_AttachmentViewer_view o_AttachmentViewer_viewIframe o_text" t-att-src="attachmentViewer.attachment.defaultSource"/>
diff --git a/addons/mail/static/src/js/document_viewer.js b/addons/mail/static/src/js/document_viewer.js
index 9ee815f9265..5325921bc5d 100644
--- a/addons/mail/static/src/js/document_viewer.js
+++ b/addons/mail/static/src/js/document_viewer.js
@@ -2,6 +2,7 @@
 
 import core from 'web.core';
 import Widget from 'web.Widget';
+import { hidePDFJSButtons } from '@web/js/libs/pdfjs';
 
 var QWeb = core.qweb;
 
@@ -74,6 +75,15 @@ var DocumentViewer = Widget.extend({
         this.modelName = 'ir.attachment';
         this._reset();
     },
+    /**
+     * Do some actions after the widget is appended to the DOM
+     * @override
+     */
+    setElement: function () {
+        const result = this._super(...arguments);
+        this._hidePdfButtonsIfPresent();
+        return result;
+    },
     /**
      * Open a modal displaying the active attachment
      * @override
@@ -101,6 +111,15 @@ var DocumentViewer = Widget.extend({
     // Private
     //---------------------------------------------------------------------------
 
+    /**
+     * Hide some buttons in PDF.js
+     * @override
+     */
+    _hidePdfButtonsIfPresent: function () {
+        if (this.activeAttachment.mimetype === 'application/pdf') {
+            hidePDFJSButtons(this.el);
+        }
+    },
     /**
      * @private
      */
@@ -137,6 +156,7 @@ var DocumentViewer = Widget.extend({
             widget: this
         }));
         this.$('.o_viewer_img').on("load", _.bind(this._onImageLoaded, this));
+        this._hidePdfButtonsIfPresent();
         this.$('[data-toggle="tooltip"]').tooltip({delay: 0});
         this._reset();
     },
diff --git a/addons/web/__manifest__.py b/addons/web/__manifest__.py
index e0b615e1800..8c0329b4f0f 100644
--- a/addons/web/__manifest__.py
+++ b/addons/web/__manifest__.py
@@ -388,6 +388,7 @@ This module provides the core of the Odoo Web Client.
             'web/static/src/js/libs/fullcalendar.js',
             'web/static/src/js/libs/jquery.js',
             'web/static/src/js/libs/underscore.js',
+            'web/static/src/js/libs/pdfjs.js',
             'web/static/src/js/libs/popper.js',
             'web/static/src/js/libs/zoomodoo.js',
             'web/static/src/js/libs/jSignatureCustom.js',
diff --git a/addons/web/static/src/js/fields/basic_fields.js b/addons/web/static/src/js/fields/basic_fields.js
index 77b7f5b7407..8a5c8a4e902 100644
--- a/addons/web/static/src/js/fields/basic_fields.js
+++ b/addons/web/static/src/js/fields/basic_fields.js
@@ -25,6 +25,7 @@ var view_dialogs = require('web.view_dialogs');
 var field_utils = require('web.field_utils');
 var time = require('web.time');
 const {ColorpickerDialog} = require('web.Colorpicker');
+const { hidePDFJSButtons } = require('@web/js/libs/pdfjs');
 
 let FieldBoolean = deprecatedFields.FieldBoolean;
 
@@ -2253,13 +2254,6 @@ var FieldPdfViewer = FieldBinaryFile.extend({
     // Private
     //--------------------------------------------------------------------------
 
-    /**
-     * @private
-     * @param {DOMElement} iframe
-     */
-    _disableButtons: function (iframe) {
-        $(iframe).contents().find('button#openFile').hide();
-    },
     /**
      * @private
      * @param {string} [fileURI] file URI if specified
@@ -2292,7 +2286,6 @@ var FieldPdfViewer = FieldBinaryFile.extend({
 
         $iFrame.on('load', function () {
             self.PDFViewerApplication = this.contentWindow.window.PDFViewerApplication;
-            self._disableButtons(this);
         });
         if (this.mode === "readonly" && this.value) {
             $iFrame.attr('src', this._getURI());
@@ -2309,6 +2302,7 @@ var FieldPdfViewer = FieldBinaryFile.extend({
                 $selectUpload.removeClass('o_hidden');
             }
         }
+        hidePDFJSButtons($iFrame[0]);
     },
 
     //--------------------------------------------------------------------------
diff --git a/addons/web/static/src/js/libs/pdfjs.js b/addons/web/static/src/js/libs/pdfjs.js
index 92c1e560001..015983fc5dc 100644
--- a/addons/web/static/src/js/libs/pdfjs.js
+++ b/addons/web/static/src/js/libs/pdfjs.js
@@ -1,5 +1,49 @@
+/** @odoo-module **/
+
+import config from 'web.config';
+
+/**
+ * Until we have our own implementation of the /web/static/lib/pdfjs/web/viewer.{html,js,css}
+ * (currently based on Firefox), this method allows us to hide the buttons that we do not want:
+ * * "Open File"
+ * * "Print" (Hidden on mobile)
+ * * "Download"
+ *
+ * @link https://mozilla.github.io/pdf.js/getting_started/
+ *
+ * @param {Element} rootElement
+ */
+export function hidePDFJSButtons(rootElement) {
+    const cssStyle = document.createElement("style");
+    cssStyle.rel = "stylesheet";
+    cssStyle.innerHTML = `button#secondaryDownload.secondaryToolbarButton, button#download.toolbarButton,
+button#secondaryOpenFile.secondaryToolbarButton, button#openFile.toolbarButton {
+display: none !important;
+}`;
+    if (config.device.isMobileDevice) {
+        cssStyle.innerHTML = `${cssStyle.innerHTML}
+button#secondaryPrint.secondaryToolbarButton, button#print.toolbarButton{
+display: none !important;
+}`;
+    }
+    const iframe = rootElement.tagName === 'IFRAME' ? rootElement : rootElement.querySelector('iframe');
+    if (iframe) {
+        if (!iframe.dataset.hideButtons) {
+            iframe.dataset.hideButtons = 'true';
+            iframe.addEventListener('load', event => {
+                if (iframe.contentDocument && iframe.contentDocument.head) {
+                    iframe.contentDocument.head.appendChild(cssStyle);
+                }
+            });
+        }
+    } else {
+        console.warn('No IFRAME found');
+    }
+}
+
 /*
-* There is no changes to pdf.js in this file, but only a note about a change that has been done in it.
+* List of changes made in the library
+* There is no changes to pdf.js in this section, but only a note about changes that has been done in /web/static/lib/pdfjs/.
 *
 * In the module account_invoice_extract, the the code need to react to the 'pagerendered' event triggered by
 * pdf.js. However in recent version of pdf.js, event are not visible outside of the library, except if the