(I'm unsure if this is a security bug.)

Hi, can you please give some more details about what the bug is here (did you upload the correct files?)

When I navigate to parent.html, nothing happens. Clicking results in this error:

Uncaught TypeError: Cannot read property 'tagName' of null
    at MyEvtHandler.utility (VM155 parent.html:3)
    at MyEvtHandler.handler (VM155 parent.html:6)
MyEvtHandler.utility @ VM155 parent.html:3
MyEvtHandler.handler @ VM155 parent.html:6

In order for this to be UXSS, you'd need the ability to read secret data from a different origin.

Er sorry, I meant to say "you'd need the ability to run script in the context of a different origin"

Oops! sorry I didn't upload the correct files. 

Deleted: parent.html 1.1 KB

parent.html 1.1 KB View Download

Deleted: child.html 1.1 KB

child.html 1.1 KB View Download

To test this, I ran a separate server on localhost:8001 and accessed parent.html via http://localhost:8001/parent.html. When I tested it that way, I get the following error:

Uncaught DOMException: Failed to execute 'dispatchEvent' on 'EventTarget': Blocked a frame with origin "http://localhost:8001" from accessing a cross-origin frame.
    at http://localhost:8001/parent.html:34:30

So this doesn't appear to work cross-origin.

I can repro this easily without any error as on the video. Could you please try with this new files inside UXSS.rar 

Deleted: UXSS.rar 1.2 KB

UXSS.rar 1.2 KB Download

Deleted: Recording.mp4 257 KB

	Recording.mp4 257 KB View Download

Hi, I am able to get the alert if I access both child.html and parent.html under the same origin, but if I try to demonstrate cross site scripting by placing them on different origins, that access seems to be blocked.

Hmm... understood :) thank you for the feedback.

All right, will close as wontfix for now, but keep the reports coming!

This bug has been closed for more than 14 weeks. Removing security view restrictions.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot