Hi Bramus!

Thank you for reaching out! I tried to reproduce the issue, but I haven't
been able to do so yet.
https://test.shhnjk.com/pen.html

It would be great if there is a page where I can see this error to
understand and investigate this further. Feel free to send me a chat
message as a follow-up!

Thanks,

Jun


On Mon, Oct 20, 2025 at 1:58 PM Bramus Van Damme <[email protected]> wrote:

> The team at CodePen are experimenting with new Pen embeds that nest two
> iframes. They are seeing a lot of "Potential permissions policy violation"
> errors in the console, as described in
> https://blog.codepen.io/2025/10/20/google-chrome-iframe-allow-permissions-problems/,
> which led them to this issue.
>
> Is it something they are doing wrong or can do better here? They also have
> a few suggestions/remarks at the end of the post. I can introduce people
> who can chime here with Chris Coyier who is the author of the post.
>
> On Wednesday, March 19, 2025 at 9:21:18 PM UTC+1 Jun Kokatsu wrote:
>
>> Great! I'll work on shipping then!
>>
>> Thanks,
>>
>> Jun
>>
>>
>> On Wed, Mar 19, 2025 at 1:19 PM Mike Taylor <[email protected]> wrote:
>>
>>> You have 3 LGTMs, so there is no need to delay shipping. Please proceed.
>>>
>>> thanks,
>>> Mike
>>> On 3/19/25 4:11 PM, Jun Kokatsu wrote:
>>>
>>> Hi All,
>>>
>>> I've file a TAG review
>>> <https://github.com/w3ctag/design-reviews/issues/1050> more than a
>>> month ago, but I'm yet to get a response.
>>> Should I wait until the TAG review is complete? Or is filing enough for
>>> shipping this feature?
>>>
>>> Thanks,
>>>
>>> Jun
>>>
>>> On Wednesday, January 29, 2025 at 8:08:15 AM UTC-8 Chris Harrelson wrote:
>>>
>>>> LGTM3
>>>>
>>>> On Wed, Jan 29, 2025 at 7:53 AM Vladimir Levin <[email protected]>
>>>> wrote:
>>>>
>>>>> LGTM2. I think this is a useful improvement over permission policy
>>>>> violation reporting
>>>>>
>>>>> On Tuesday, January 28, 2025 at 10:15:57 AM UTC-5 Mike Taylor wrote:
>>>>>
>>>> LGTM1
>>>>>> On 1/27/25 6:27 PM, 'Jun Kokatsu' via blink-dev wrote:
>>>>>>
>>>>>> On Sunday, January 26, 2025 at 6:45:39 PM UTC-8 Domenic Denicola
>>>>>> wrote:
>>>>>>
>>>>>>
>>>>>>
>>>>>> On Friday, January 17, 2025 at 7:42:03 AM UTC+9 Jun Kokatsu wrote:
>>>>>>
>>>>>> Contact [email protected]
>>>>>>
>>>>>> Specificationhttps://github.com/w3c/webappsec-permissions-policy/
>>>>>> pull/546
>>>>>>
>>>>>>
>>>>>>
>>>>>> Summary
>>>>>>
>>>>>> Introduces a new violation type called "Potential Permissions Policy
>>>>>> violation", which will only look at Permissions Policy (including
>>>>>> report-only policy) and the allow attribute set in iframes to detect the
>>>>>> conflict between Permissions Policy enforced vs permissions propagated to
>>>>>> iframes.
>>>>>>
>>>>>> Motivation
>>>>>> Permissions Policy violation reports for cross-origin iframes are
>>>>>> only sent to the iframe's reporting endpoint and not to the embedder's
>>>>>> reporting endpoint, because of the concern that it might leak sensitive
>>>>>> information about a cross-origin iframe. However, this makes it difficult
>>>>>> for sites to enforce Permissions Policy because it can't learn about
>>>>>> breakages in cross-origin iframes. This feature introduces a new 
>>>>>> violation
>>>>>> type called "Potential Permissions Policy violation", which will only 
>>>>>> look
>>>>>> at existing Permissions Policy (including report-only policy) and the 
>>>>>> allow
>>>>>> attribute set in iframes to detect the conflict between Permissions 
>>>>>> Policy
>>>>>> enforced vs permissions being propagated to iframes. Since both 
>>>>>> Permissions
>>>>>> Policy and allow attributes are set by the embedder, this feature does 
>>>>>> not
>>>>>> leak any new information to the embedder. However, potential Permissions
>>>>>> Policy violations will be sent when an iframe is loaded, and not when the
>>>>>> iframe uses the prohibited feature, which is different from the normal
>>>>>> Permissions Policy violations which fires upon a feature usage (hence the
>>>>>> name "potential").
>>>>>>
>>>>>> Blink componentBlink>PermissionsPolicy
>>>>>> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EPermissionsPolicy%22>
>>>>>>
>>>>>> TAG reviewNone
>>>>>>
>>>>>> TAG review statusNot applicable
>>>>>>
>>>>>>
>>>>>> Can you say more why you believe TAG review is not applicable for
>>>>>> this feature? I cannot figure out which exception, if any, it falls under
>>>>>> from this list
>>>>>> <https://www.chromium.org/blink/launching-features/wide-review/#exceptions>
>>>>>> .
>>>>>>
>>>>>>
>>>>>> Sorry, I think I missed this step. I will submit for a TAG review,
>>>>>> and come back to this thread once the TAG review is approved.
>>>>>>
>>>>>> FWIW, I don't think we should block on TAG review resolution - but
>>>>>> it's useful to file an issue, in case someone is keeping track of APIs 
>>>>>> that
>>>>>> do reporting, or have report-only modes.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Risks
>>>>>>
>>>>>>
>>>>>> Interoperability and Compatibility
>>>>>>
>>>>>> None
>>>>>>
>>>>>>
>>>>>> *Gecko*: No signal
>>>>>> <https://github.com/mozilla/standards-positions/issues/1164>
>>>>>>
>>>>>> *WebKit*: No signal
>>>>>> <https://github.com/WebKit/standards-positions/issues/448>
>>>>>>
>>>>>> *Web developers*: No signals
>>>>>>
>>>>>>
>>>>>> Why are we proposing to ship this, if it is not interesting to any
>>>>>> web developers, and has support from no other browsers?
>>>>>>
>>>>>>
>>>>>> We'd like to mitigate Permission Delegation of powerful permissions
>>>>>> to unintentional sites (e.g. HTML injection in Bing resulted in
>>>>>> camera access in Edge
>>>>>> <https://speakerdeck.com/shhnjk/piloting-edge-copilot?slide=27>) in
>>>>>> Google applications.
>>>>>> So we do have internal developer support. But I'm not sure if there
>>>>>> is external developer support.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> *Other signals*:
>>>>>>
>>>>>> Security
>>>>>>
>>>>>> Potential Permissions Policy violation reports should not include any
>>>>>> new information about cross-origin iframes
>>>>>>
>>>>>>
>>>>>> WebView application risks
>>>>>>
>>>>>> Does this intent deprecate or change behavior of existing APIs, such
>>>>>> that it has potentially high risk for Android WebView-based applications?
>>>>>>
>>>>>> None
>>>>>>
>>>>>>
>>>>>> Debuggability
>>>>>>
>>>>>> None
>>>>>>
>>>>>>
>>>>>> Will this feature be supported on all six Blink platforms (Windows,
>>>>>> Mac, Linux, ChromeOS, Android, and Android WebView)?No
>>>>>>
>>>>>>
>>>>>> Which platform will it not be supported on?
>>>>>>
>>>>>>
>>>>>> This had to be Yes. I've fixed it in Chrome status.
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>>
>>>>>> Is this feature fully tested by web-platform-tests
>>>>>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>
>>>>>> ?https://github.com/web-platform-tests/wpt/pull/49978
>>>>>>
>>>>>>
>>>>>>
>>>>>> Flag name on about://flagsNone
>>>>>>
>>>>>> Finch feature namePotentialPermissionsPolicyReporting
>>>>>>
>>>>>> Requires code in //chrome?False
>>>>>>
>>>>>> Tracking bughttps://issues.chromium.org/issues/40941424
>>>>>>
>>>>>> Estimated milestonesShipping on desktop134
>>>>>>
>>>>>> Anticipated spec changes
>>>>>>
>>>>>> Open questions about a feature may be a source of future web compat
>>>>>> or interop issues. Please list open issues (e.g. links to known github
>>>>>> issues in the project for the feature specification) whose resolution may
>>>>>> introduce web compat/interop risk (e.g., changing to naming or structure 
>>>>>> of
>>>>>> the API in a non-backward-compatible way).
>>>>>> None
>>>>>>
>>>>>> Link to entry on the Chrome Platform Statushttps://chromestatus.com/
>>>>>> feature/5154241037205504?gate=5069369228656640
>>>>>>
>>>>>>
>>>>>>
>>>>>> This intent message was generated by Chrome Platform Status
>>>>>> <https://chromestatus.com/>.
>>>>>>
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>>>>>>
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>>>>>> send an email to [email protected].
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>>>>>>
>>>>>> To view this discussion visit
>>>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/453d70c8-b1b4-4607-8a76-ff564f00b231n%40chromium.org
>>>>>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/453d70c8-b1b4-4607-8a76-ff564f00b231n%40chromium.org?utm_medium=email&utm_source=footer>
>>>>>> .
>>>>>>
>>>>>> --
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>>>>> To view this discussion visit
>>>>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/5f98e6ec-8ea6-4982-ad4c-44d88c48ec3dn%40chromium.org
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>>>>> .
>>>>>
>>>>

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