Random 403 Forbidden errors when embedding external v0 domain in iframe

Help
1

Hi!

Im building a portfolio site that embeds my projects in iframes. Multiple projects randomly returns 403 Forbidden when embedded on my main site

What I’ve done:

  • Tried using a custom domain and original .vercel.app domain

  • Added Content-Security-Policy header in vercel.json:

  • Disabled Vercel Authentication

  • Redeployed the project

  • Cleared browser cache and cookies

  • Tested on mobile hotspot (different network)

Behavior:

  • Works randomly Safari, Chrome incognito, mobile browser

  • Inconsistent across users and browsers

Error details:

403: ForbiddenID: bom1::xj5fr-1778227176584-f8bef962b18a

Any ideas what could be causing this?

2

Same, did you find a fix?

3

You can follow this thread, we all have related issues.

4

Thanks for sharing! Seems like there are no answers yet

5

Hi Vignesh,

Since this happens specifically when the project is embedded in an iframe, I would separate two possible causes:

  1. The iframe is being blocked by headers/browser policy.

  2. Vercel is returning a real 403: Forbidden before the page loads.

The quickest way to narrow it down is to open DevTools on the parent page and check the failing iframe request in the Network tab.

Useful things to check:

  • Does the iframe request itself return 403, or is the browser blocking it because of X-Frame-Options / Content-Security-Policy?

  • Does the same deployment URL work when opened directly in a normal tab?

  • Are all affected projects under the same Vercel account/team?

  • Are Deployment Protection, Vercel Authentication, or Firewall rules enabled on any of the embedded projects?

  • Does the 403 include a Vercel request ID every time?

If the direct URL works but iframe access randomly gets 403, I would include the parent domain, embedded domain, failing request ID, and browser/network details so Vercel staff can check whether the request is being blocked by protection/firewall logic or by app headers.

6

Hi! It got resolved with the recent 403 fix but thanks for the thorough help again!

7

Glad it was resolved, and thanks for confirming.

If the issue is fully fixed now, could you mark the topic as solved or close it? That should make it easier for others who run into the same 403 iframe issue to see that it was resolved by the recent 403 fix.