CVE-2022-23494 (published 2022-12-08T22:15Z)

tinymce is an open source rich text editor. A cross-site scripting (XSS) vulnerability was discovered in the alert and confirm dialogs when these dialogs were provided with malicious HTML content. This can occur in plugins that use the alert or confirm dialogs, such as in the `image` plugin, which presents these dialogs when certain errors occur. The vulnerability allowed arbitrary JavaScript execution when an alert presented in the TinyMCE UI for the current user. This vulnerability has been patched in TinyMCE 5.10.7 and TinyMCE 6.3.1 by ensuring HTML sanitization was still performed after unwrapping invalid elements. Users are advised to upgrade to either 5.10.7 or 6.3.1. Users unable to upgrade may ensure the the `images_upload_handler` returns a valid value as per the images_upload_handler documentation.

CVSS v3 base score: 6.1, MEDIUM (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)

Weakness information:
cwe_id: CWE-79
cwe_name: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
description: The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.
extended_description: 
            Cross-site scripting (XSS) vulnerabilities occur when:
            
               Untrusted data enters a web application, typically from a web request.
               The web application dynamically generates a web page that contains this untrusted data.
               During page generation, the application does not prevent the data from containing content that is executable by a web browser, such as JavaScript, HTML tags, HTML attributes, mouse events, Flash, ActiveX, etc.
               A victim visits the generated web page through a web browser, which contains malicious script that was injected using the untrusted data.
               Since the script comes from a web page that was sent by the web server, the victim's web browser executes the malicious script in the context of the web server's domain.
               This effectively violates the intention of the web browser's same-origin policy, which states that scripts in one domain should not be able to access resources or run code in a different domain.
            
            There are three main kinds of XSS:
            
               
                  Type 1: Reflected XSS (or Non-Persistent) - 
         			The server reads data directly from the HTTP request and reflects it back in the HTTP response. Reflected XSS exploits occur when an attacker causes a victim to supply dangerous content to a vulnerable web application, which is then reflected back to the victim and executed by the web browser. The most common mechanism for delivering malicious content is to include it as a parameter in a URL that is posted publicly or e-mailed directly to the victim. URLs constructed in this manner constitute the core of many phishing schemes, whereby an attacker convinces a victim to visit a URL that refers to a vulnerable site. After the site reflects the attacker's content back to the victim, the content is executed by the victim's browser.
               
                  Type 2: Stored XSS (or Persistent) - 
               The application stores dangerous data in a database, message forum, visitor log, or other trusted data store. At a later time, the dangerous data is subsequently read back into the application and included in dynamic content. From an attacker's perspective, the optimal place to inject malicious content is in an area that is displayed to either many users or particularly interesting users. Interesting users typically have elevated privileges in the application or interact with sensitive data that is valuable to the attacker. If one of these users executes malicious content, the attacker may be able to perform privileged operations on behalf of the user or gain access to sensitive data belonging to the user. For example, the attacker might inject XSS into a log message, which might not be handled properly when an administrator views the logs.
            
               
                  Type 0: DOM-Based XSS - 
               In DOM-based XSS, the client performs the injection of XSS into the page; in the other types, the server performs the injection. DOM-based XSS generally involves server-controlled, trusted script that is sent to the client, such as Javascript that performs sanity checks on a form before the user submits it. If the server-supplied script processes user-supplied data and then injects it back into the web page (such as with dynamic HTML), then DOM-based XSS is possible.
            
            
            Once the malicious script is injected, the attacker can perform a variety of malicious activities. The attacker could transfer private information, such as cookies that may include session information, from the victim's machine to the attacker. The attacker could send malicious requests to a web site on behalf of the victim, which could be especially dangerous to the site if the victim has administrator privileges to manage that site. Phishing attacks could be used to emulate trusted web sites and trick the victim into entering a password, allowing the attacker to compromise the victim's account on that web site. Finally, the script could exploit a vulnerability in the web browser itself possibly taking over the victim's machine, sometimes referred to as "drive-by hacking."
            In many cases, the attack can be launched without the victim even being aware of it. Even with careful users, attackers frequently use a variety of methods to encode the malicious portion of the attack, such as URL encoding or Unicode, so the request looks less suspicious.
         
         

Fix information:
repo_url: https://github.com/tinymce/tinymce
commit_details: repo_url: https://github.com/tinymce/tinymce
author: spocke
author_date: 2022-12-06 02:02:46+01:00
msg: Merge pull request from GHSA-gg8r-xjwq-4w92

* TINY-3548: sanitize html in alert/confirm messages

* TINY-3548: updated changelog

* TINY-3548: updated changelog

* TINY-3548: updated changelog
repository: repo_url: https://github.com/tinymce/tinymce
repo_name: tinymce/tinymce
description: The world's #1 JavaScript library for rich text editing. Available for React, Vue and Angular
repo_language: TypeScript
owner: tinymce
file_changes: filename: CHANGELOG.md
change_type: ModificationType.MODIFY
diff: @@ -6,6 +6,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Fixed
+- HTML in messages for the `WindowManager.alert` and `WindowManager.confirm` APIs were not properly sanitized. #TINY-3548
+
 ## 6.3.0 - 2022-11-23
 
 ### Added

programming_language: Markdown
filename: HtmlSanitizer.ts
change_type: ModificationType.ADD
diff: @@ -0,0 +1,3 @@
+import createDompurify from 'dompurify';
+
+export const sanitizeHtmlString = (html: string): string => createDompurify().sanitize(html);

programming_language: TypeScript
filename: Dialogs.ts
change_type: ModificationType.MODIFY
diff: @@ -8,6 +8,7 @@ import { Class, SugarBody } from '@ephox/sugar';
 import Env from 'tinymce/core/api/Env';
 
 import { UiFactoryBackstageProviders } from '../../backstage/Backstage';
+import * as HtmlSanitizer from '../core/HtmlSanitizer';
 import * as NavigableObject from '../general/NavigableObject';
 
 const isTouch = Env.deviceType.isTouch();
@@ -77,7 +78,7 @@ const pBodyMessage = (message: string, providersBackstage: UiFactoryBackstagePro
       },
       components: [
         {
-          dom: DomFactory.fromHtml(`<p>${providersBackstage.translate(message)}</p>`)
+          dom: DomFactory.fromHtml(`<p>${HtmlSanitizer.sanitizeHtmlString(providersBackstage.translate(message))}</p>`)
         }
       ]
     }

programming_language: TypeScript
filename: WindowManagerAlertTest.ts
change_type: ModificationType.MODIFY
diff: @@ -184,4 +184,41 @@ describe('headless.tinymce.themes.silver.window.WindowManagerAlertTest', () => {
     Mouse.clickOn(SugarBody.body(), '.tox-button:contains("OK")');
     UiFinder.notExists(SugarBody.body(), '[role="dialog"]');
   });
+
+  it('TINY-3548: sanitize message', async () => {
+    createAlert('<a href="javascript:alert(1)">invalid link</a><script>alert(1)</script><a href="http://tiny.cloud">valid link</a>', Fun.noop);
+    const dialogBody = SelectorFind.descendant(SugarDocument.getDocument(), '.tox-dialog__body').getOrDie('Cannot find dialog body element');
+    Assertions.assertStructure('A basic alert dialog should have these components',
+      ApproxStructure.build((s, str, arr) => s.element('div', {
+        classes: [ arr.has('tox-dialog__body') ],
+        children: [
+          s.element('div', {
+            classes: [ arr.has('tox-dialog__body-content') ],
+            children: [
+              s.element('p', {
+                children: [
+                  s.element('a', {
+                    exactAttrs: { },
+                    children: [
+                      s.text(str.is('invalid link'))
+                    ]
+                  }),
+                  s.element('a', {
+                    exactAttrs: {
+                      href: str.is('http://tiny.cloud')
+                    },
+                    children: [
+                      s.text(str.is('valid link'))
+                    ]
+                  })
+                ]
+              })
+            ]
+          })
+        ]
+      })),
+      dialogBody
+    );
+    await pTeardown();
+  });
 });

programming_language: TypeScript
filename: WindowManagerConfirmTest.ts
change_type: ModificationType.MODIFY
diff: @@ -195,4 +195,41 @@ describe('headless.tinymce.themes.silver.window.WindowManagerConfirmTest', () =>
     Mouse.clickOn(SugarBody.body(), '.tox-button:contains("Yes")');
     UiFinder.notExists(SugarBody.body(), '[role="dialog"]');
   });
+
+  it('TINY-3548: sanitize message', async () => {
+    createConfirm('<a href="javascript:alert(1)">invalid link</a><script>alert(1)</script><a href="http://tiny.cloud">valid link</a>', Fun.noop);
+    const dialogBody = SelectorFind.descendant(SugarDocument.getDocument(), '.tox-dialog__body').getOrDie('Cannot find dialog body element');
+    Assertions.assertStructure('A basic alert dialog should have these components',
+      ApproxStructure.build((s, str, arr) => s.element('div', {
+        classes: [ arr.has('tox-dialog__body') ],
+        children: [
+          s.element('div', {
+            classes: [ arr.has('tox-dialog__body-content') ],
+            children: [
+              s.element('p', {
+                children: [
+                  s.element('a', {
+                    exactAttrs: { },
+                    children: [
+                      s.text(str.is('invalid link'))
+                    ]
+                  }),
+                  s.element('a', {
+                    exactAttrs: {
+                      href: str.is('http://tiny.cloud')
+                    },
+                    children: [
+                      s.text(str.is('valid link'))
+                    ]
+                  })
+                ]
+              })
+            ]
+          })
+        ]
+      })),
+      dialogBody
+    );
+    await pTeardown();
+  });
 });

programming_language: TypeScript