Contain XSS Risks
Reduce the risk of cross-site scripting attacks by restricting scripts and or requests.
Block data exfiltration from compromised web apps
Cross-site scripting (XSS) remains one of the most exploited vectors in web attacks—especially in apps you don’t control. Without the ability to set Content Security Policies (CSP) server-side, security teams are left with few options.
Webfuse gives you that control—without touching the backend.
Apply outbound domain allowlists at the session level, ensuring compromised apps can’t leak data to unauthorized domains.
CSP isn’t available everywhere—especially on SaaS & legacy platforms
- You can’t modify CSP headers in third-party apps
- Malicious scripts can still run inside compromised or misconfigured pages
- Once in, attackers can exfiltrate data by sending requests elsewhere
- Teams lack frontend control to stop this behavior
How Webfuse solves this
Lock Down Outbound Traffic with a Domain Allowlist
Using Webfuse’s Lockdown App, you can:
- *Create an allowlist of permitted domains (e.g., .example.com)
- Prevent any navigation, script load, or API call to unlisted domains
- Apply this policy at the Virtual Web Session level, instantly
Key benefits
- Reduce Impact of XSS Attacks: Rogue scripts can’t send data outside your defined scope
- No Backend Access Needed: Apply security at the session edge
- Protect Users of SaaS, Portals, or Legacy Apps: Even those you don’t host
Examples
- Protect Government Portals from Rogue Redirects
- Limit Vendor Apps from Calling External Scripts
- Harden Internal Tools That Can’t Be Patched
Sign up & get started
Launch a SPACE with outbound domain restrictions. Our Lockdown App is pre-installed with sample allowlists to get started instantly.
FAQ
Can I use Webfuse to prevent scripts from running inside a web app?
No, Webfuse doesn’t alter a site’s internal JS behavior directly. Instead, it restricts external communications by applying domain-level restrictions—so even if malicious scripts run, they cannot exfiltrate data.
Do I need developer access to the original app to apply restrictions?
Not at all. Webfuse applies the restrictions via Virtual Web Sessions—no backend or server-side access is needed.
Can I combine this with a Content Security Policy?
Yes! You can inject CSP headers via the Custom Headers App to add another layer of protection on top of domain allowlisting.
What happens if the app tries to call an unapproved domain?
The request will be blocked within the session, and depending on the browser, users may see a generic failure or nothing at all—ensuring no data leaves your allowed scope.
