Copy and pasted images to issues containing a '/' (forward slash) cannot be viewed in GUI and they result in 400 errors (malformed request)

Issue Summary

Copy and pasted images, screenshots to issues which contain a '/' (forward slash) in the filename cannot be viewed and system with throw 400 errors (malformed request).

This is reproducible on Data Center: (yes)

Steps to Reproduce

1. Create a screen shot or copy an entire image from any image tool (Ctrl-C).
2. Paste it into the issue while pressing Ctrl-V.
3. Attach screenshot pop-up will appear.
4. In the filename dialog add a '/' to the file name anywhere and click "Upload".
5. The file gets saved successfully and we could see in thumbnails.
6. Now try to access this image newly added and observe the pattern.

Expected Results

System should allow the users to access these attachments as they are uploaded and thumbnails clearly show the screenshots attached.
 

Actual Results

The system throws errors in GUI mentioning 400 error due to malformed request. HAR file indicates the error mentioned below in the response of the request.

Since this is a client error, no error reported in the logs for this operation.

The server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing). 

Workaround

Please don't use '/' character in the filenames when directly adding as attachments. Otherwise system will block access to those attachments due to malformed requests while trying to fetch them resulting in 400 errors.