Examples don't work due to DOMException: Blocked a frame with origin "https://fiddle.jshell.net"

[muuki88]

Examples don't work due to issues with jsfiddle: https://docs.prebid.org/dev-docs/examples/basic-example.html

Uncaught DOMException: Blocked a frame with origin "https://fiddle.jshell.net" from accessing a cross-origin frame.
    at Object.6260 (https://cdn.jsdelivr.net/npm/prebid.js@latest/dist/not-for-prod/prebid.js:122:133)
    at r (https://cdn.jsdelivr.net/npm/prebid.js@latest/dist/not-for-prod/prebid.js:4:138148)
    at https://cdn.jsdelivr.net/npm/prebid.js@latest/dist/not-for-prod/prebid.js:122:458
    at n (https://cdn.jsdelivr.net/npm/prebid.js@latest/dist/not-for-prod/prebid.js:4:139393)
    at https://cdn.jsdelivr.net/npm/prebid.js@latest/dist/not-for-prod/prebid.js:122:50

[dgirardi]

Introduced by prebid/Prebid.js#8364 . cpexIdSystem would cause this in any cross-origin scenario.

Tagging @EskelCz

[EskelCz]

@dgirardi Sorry I'm confused.

1. Our module is not even configured there
2. It just tries to read a 1st party cookie, why would it block an iframe?

Do you have some idea what's going on?

[dgirardi]

Sorry - I should have been more specific. the problem is

window.top.cpexIdVersion = '0.0.3'

Writing to window.top will throw an exception if cross-origin. The examples use a version of prebid with all modules installed, and that line is in the main body of the module - it's enough to install it to get the exception.

[EskelCz]

@dgirardi I see, that makes sense. Thanks for figuring it out.
Here's a fix: prebid/Prebid.js#8440
(If I can move the version into the submodule, so it's still accessible programatically in some way)