2067493 - Thunderbird 154.0: Cutting embedded images from a forwarded HTML email exposes Base64 data URI

Status: RESOLVED DUPLICATE of bug 2061788

(Thunderbird :: Message Compose Window, defect)

Description

[Reiner]

Attachment: Screenshot 2026-08-29 154612.png

User Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/152.0.0.0 Safari/537.36

Steps to reproduce:

1. Open an existing HTML email containing embedded JPEG images.
2. Forward the email.
3. Select one of the embedded images in the compose window.
4. Press Ctrl+X to cut the image.
5. The issue also occurs when trying to move the image within the forwarded message.
   As a control test, I created a new email and inserted a JPEG using Thunderbird's image insertion function. Ctrl+X works correctly with this newly inserted image.
   The problem therefore appears to affect images inherited from an existing HTML email when forwarding.

Actual results:

After pressing Ctrl+X, the embedded image is not simply removed. Instead, its complete data URI / Base64 encoded content becomes visible as text in the compose window, starting with:
data:image/jpeg;filename=...;base64,/9j/4AAQ...
This makes it impossible to move or cut the inherited image normally.

Expected results:

The selected image should be removed from its original position and placed on the clipboard, so that it can be pasted at another position in the message.
No Base64 data or data URI should become visible in the message body.