Image previews not shown

[weebl2000]

Steps to reproduce

If images are sent to a room without an extension in the name there are no previews anymore in the Desktop app. Mediatype is supplied.

This has worked fine for years until a few months ago. I had hoped it would get fixed but it's still happening. On Element Android / iOS app the images still load fine using the same message.

Source message example:

{
  "type": "m.room.message",
  "sender": "@user:server.com",
  "content": {
    "msgtype": "m.image",
    "body": "Blabla",
    "url": "mxc://matrix.server.me/idishere",
    "info": {
      "mimetype": "image/gif"
    }
  },
  "origin_server_ts": <snip>,
  "unsigned": {
    <snip>
  },
  "event_id": "$",
  "room_id": "!x"
}

Outcome

What did you expect?

Image preview shows.

What happened instead?

Image is shown as an attachment link.

Operating system

Linux, Windows

Application version

1.11.89

How did you install the app?

No response

Homeserver

No response

Will you send logs?

Yes

[t3chguy]

This is done for security, the body field of the event is specified to be the filename if the filename field is missing. When downloaded, a mismatched extension could be executed. E.g. if you have an "image" called "foo.exe" with mimetype image/png it would still be executed by your OS unless you have security cranked up. See GHSA-5486-384g-mcx2

[weebl2000]

Why not just add the extension associated with the mediatype upon downloading? Seems safer than the current solution.

[t3chguy]

Because when downloading you can't always specify the filename, it may be specified by the Matrix homeserver instead which does not allow a way to be overriden.