Embed Mode: Can't open files

[jotwg]

Describe the bug

When opening OC in an iFrame in a self hosted HumHub instance I can't open existing files for viewing/editing.

Steps to reproduce

1. Open embedded OC via link on a custom page of type iFrame in HumHub.
2. Click an entry in the file list

Expected behavior

Click on an entry in the file list should open the respective file with according app (text editor, collabora)

Actual behavior

Entry will be marked/unmarked as selected but it does not open for viewing/editing. When opening OC in a separate browser tab every thing is working as expected.

Setup

• HumHub and OC are running behind a nginx proxy.
• Authentication is done via Keycloak
• OC is embedded via a "Custom Page" of type iFrame
• Target Url is just "https://<my OC domain>/?embed=true"

Additional context

CSP headers etc. are set in nginx:

curl -I https://my_OC_domain:

HTTP/1.1 200 OK
Server: nginx
Date: Thu, 27 Nov 2025 14:55:54 GMT
Content-Type: text/html; charset=utf-8
Connection: keep-alive
Cache-Control: no-cache
Last-Modified: Sun, 23 Nov 2025 16:35:43 GMT
Referrer-Policy: strict-origin-when-cross-origin
Samesite: Strict
Vary: Origin
X-Content-Type-Options: nosniff
X-Permitted-Cross-Domain-Policies: none
X-Request-Id: ee62b4c84952/c3ziYdSHnc-003093
X-Robots-Tag: none
X-Web-Version: 4.0.0-rc.1
X-Xss-Protection: 1; mode=block
Content-Security-Policy: frame-ancestors 'self' https://<my HumHub domain> http://<my HumHub domain>
X-Frame-Options: ALLOW-FROM https://<my keycloak domain> http://<my HumHub domain> https://<my HumHub domain>