One comment.
One compromised account.
A script hidden in an internal forum is enough to steal a manager's session. No suspicious click. No download. No alert. The browser runs the code the moment the page opens.
Marc Charpentier
2h ago · HR Generalist
Great meeting this morning! The new onboarding process is really well thought out.
Nadia Bertin
1h ago · Payroll Manager
Agreed with Marc. The checklist shared yesterday is very useful for new hires.
Unknown account
5 min ago · External access
Great article! Very useful for the team.
An internal forum open to everyone
Every comment is stored and then shown to all team members
The vector: any free-text input field
Forums, comment sections, search fields, contact forms. Anywhere a user can write text that's later shown to others, an XSS flaw can exist if the data isn't handled properly.
Key figures
#0
OWASP Top 10
Injection (incl. XSS)
0
Clicks required
for Stored XSS
∞
Potential victims
per stored comment
< 0s
To steal a cookie
via a silent fetch()
Concrete impact for your organization
A stolen session grants access to the account with no password, no alert, often without the victim even noticing. A single script injected into an internal tool (intranet, ticketing, chat) is enough to compromise dozens of accounts within hours.
Technical demo
Try it yourself
This simulation lets you inject a real XSS payload and watch its behavior in a controlled environment. Intended for technical teams and trainers.
Interactive demo
Inject an XSS payload
No injection simulated
Choose a payload or type your own, then click Simulate
Stored vs Reflected
A stored XSS persists in the database — every visitor becomes a victim. A reflected XSS only exploits the session of whoever clicks a rigged link.
How to protect against it
- Escape HTML server-side before rendering
- Strict Content Security Policy (CSP)
- Cookies marked
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