From a911f95771cb1a8fb2a0dcaaeae290e8bba5137a Mon Sep 17 00:00:00 2001
From: VaseegaranSF4468 <162665726+VaseegaranSF4468@users.noreply.github.com>
Date: Wed, 6 May 2026 19:53:17 +0530
Subject: [PATCH 1/6] 1013927: Updated the Cross-Site Scripting UG
documentation
---
.../cross-site-scripting-prevention.md | 106 ++++++------------
1 file changed, 36 insertions(+), 70 deletions(-)
diff --git a/blazor/common/security/cross-site-scripting-prevention.md b/blazor/common/security/cross-site-scripting-prevention.md
index 37e08dd42f..508d9e8371 100644
--- a/blazor/common/security/cross-site-scripting-prevention.md
+++ b/blazor/common/security/cross-site-scripting-prevention.md
@@ -11,69 +11,35 @@ documentation: ug
## Overview
-[Cross-Site Scripting (XSS)](https://developer.mozilla.org/en-US/docs/Web/Security/Attacks/XSS) is one of the most common security problems in web applications. This guide explains how to protect [Syncfusion® Blazor components](https://www.syncfusion.com/blazor-components) from XSS attacks. It covers built-in client-side sanitization, server-side validation, and safe usage guidelines for components that handle user‑generated content.
+[Cross-Site Scripting (XSS)](https://developer.mozilla.org/en-US/docs/Web/Security/Attacks/XSS) is one of the most common security vulnerabilities in web applications. It occurs when attackers inject malicious scripts or markup into an application, causing untrusted content to execute in the user’s browser with the same privileges as the application.
-## What is Cross-Site Scripting (XSS)?
-
-XSS is a vulnerability where attackers insert harmful code into your application, causing it to run in the user’s browser with the same access level as your app. This can result in:
-
-- **Session hijacking** - Stealing authentication tokens or cookies
-- **Data theft** - Accessing sensitive user information
-- **Malware distribution** - Redirecting users to malicious sites
-- **UI manipulation** - Altering what users see on the screen
-- **Credential theft** - Capturing information entered into forms, such as usernames or passwords
+This guide explains how to protect [Syncfusion® Blazor components](https://www.syncfusion.com/blazor-components) from XSS attacks. It covers built-in client-side sanitization, required server-side validation, and safe usage guidelines for components that handle user-generated content.
### Types of XSS attacks
-1. **Stored XSS** - The attacker injects malicious code through user input (e.g., a form field) which is then stored in your database. The code executes whenever another user loads the affected page. This is the most dangerous type.
-2. **Reflected XSS** - The harmful script is delivered through a URL or form input and is immediately sent back in the response, causing it to execute in the user’s browser.
-3. **DOM-based XSS** - Client-side scripts read unsafe data and write it directly into the page.
+1. **Stored XSS** – Malicious scripts are saved in the application and executed in the user’s browser when the content is loaded.
+2. **Reflected XSS** – Malicious input is returned in the server response and executed in the browser.
+3. **DOM-based XSS** – Client-side scripts read untrusted data and write it directly into the page.
## Why XSS matters in Blazor applications?
-Blazor Server and Blazor WebAssembly come with different types of XSS risks.
+Blazor Server and Blazor WebAssembly have different XSS risks due to their execution models.
### Blazor Server
-- All logic runs on the server, so validation is easier, but XSS can still happen if unsafe content is displayed.
-- If an XSS attack happens, an attacker could potentially take control of the SignalR connection that Blazor depends on.
-- The user's session state and backend resources could be compromised.
+- XSS can occur if unsafe content is rendered without proper sanitization.
+- A successful XSS attack could potentially interfere with the SignalR connection used by Blazor Server.
+- User session state and backend resources may be exposed or misused.
### Blazor WebAssembly
-- The application runs entirely in the user's browser. Injected scripts execute locally and can modify the user interface or hijack user sessions.
-- Client-side files and application logic are publicly available. This makes it easier for attackers to inspect or bypass client-side protections.
-- Never store secrets or other sensitive data in the browser. Protect API endpoints with server-side authentication and authorization.
-- Client-side validation and sanitization improve the user experience but are not a substitute for server-side validation and sanitization. Always validate and sanitize all client-origin data on the server.
+- The application runs entirely in the user’s browser, so injected scripts execute locally and can manipulate the UI or access user data.
+- Client-side code and files are publicly accessible, making client-only protections easier to inspect or bypass.
+- Relying only on client-side validation and sanitization increases XSS risk, as attackers can bypass these mechanisms and allow malicious payloads to reach backend services when server-side validation is missing.
## XSS threat model and attack vectors
-### Common attack vectors
-
-XSS can enter an application in many different ways. The most common source is user input, such as comments, chat messages, or any data that users type into forms. Data received from APIs, uploaded files, or text copied from other websites can also contain harmful scripts. Even information already stored in the database may be unsafe if it was not validated or sanitized before being saved.
-
-### Example attack payloads
-
-{% tabs %}
-{% highlight html %}
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