AuthorizeNetIFrame.onReceiveCommunication not firing on localhost (sandbox) – suddenly stopped work

[avalynn]

Hi team,

The on Receive Communication handler suddenly stopped firing on localhost in sandbox while everything still works perfectly on staging.

• Transaction is processed successfully in sandbox
• No transact  Response is ever posted back to parent page
• Handler is bound correctly on page load (confirmed with console.log)
• No breakpoints hit, not even on initial i frame load
• Was working fine until early November 2025
• Using latest PHP SDK (updated Oct 2024)
• Full HTTPS with valid cert, no mixed content

Staging server (public domain) works 100%. Only localhost is broken.

Have there been any recent sandbox/CSP changes that now block post Message to localhost/custom domains? Do I need to add something to IFrameCommunicator.html headers or whitelist my   site. local somewhere?

Thanks for any quick pointers!

[aacampillo]

I started getting CSP-related issues in the Sandbox and posted about it here: https://community.developer.cybersource.com/t5/Integration-and-Testing/Accept-Hosted-iFrame-Sandbox-...

So we ae dead in the water because we can't change anything about the auth.net form embedded in the iFrame. I also submitted a support ticket. I'm not sure if this is the exact same, but it sounds like it.