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Resolving Pwnbox VNC Resizing Issues

Experiencing continuous screen resizing issues with your Pwnbox VNC client when viewing it in Full Screen? This troubleshooting guide will help you resolve the continuous resize event spam so you can bypass the bug.

Written by htblxck

Resolving Pwnbox VNC Resizing Issues

Understanding the Root Cause

This issue is a visual calculation bug specific to the VNC client, not a network or region issue.

When you apply browser zoom or scale your browser to match zoom levels between viewer and preview tabs, your browser creates decimal pixel values. The noVNC client requires whole numbers (AKA integers) for element-sizing calculations.

When the client receives these decimal values, it continuously spams resize events, and therefore, you cannot properly resize your Pwnbox with the usual workarounds of refreshing or resizing the browser window. This same conflicting element is also the cause of the Pwnbox showing as "Disconnected" when you try to resize, fullscreen, or open it in a new tab - the workaround below resolves that case as well.

This is not a one-time fix. Because the underlying bug is still present, the resize glitch will come back any time you refresh the page, reload the module/exam tab, or start a new session. You will need to re-apply one of the methods below every time this happens, not just the first time.

Applying the Workaround

While our team works on a permanent fix, you can use your browser's developer tools (DevTools) console or address bar to remove the conflicting visual element. This will restore your ability to use the VNC client in full screen.

Method 1: Changing your Browser's Zoom:

  1. Navigate to the tab on your browser where you have your section's text content open (this is the tab where you are reading the course – not the one that opens after you make your Pwnbox fullscreen). It should look similar to this:

  2. Move your mouse all the way to the right side of your address bar, and you should see a Magnifying Glass (Zoom) icon. If you don't see this icon, press either CTRL + + and you should see it afterwards. It should look like this:

  3. Refresh the page where your Pwnbox is open in full-screen mode. The page's URL should start with vnc.htb-cloud.com.... Similar to this:

  4. After that, your Pwnbox should be resized correctly. Here's how the whole process looks:

Method 2: Using the Browser Console (DevTools)

  1. Navigate to the tab on your browser where you have your section's text content open (this is the tab where you are reading the course – not the one that opens after you make your Pwnbox fullscreen). It should look similar to this:

  2. Open your browser's Developer Tools by pressing F12 or by right-clicking anywhere on the page and selecting "Inspect":

  3. Click on the "Console" tab – as shown in the image above.

  4. Paste the following command into the console: document.getElementById('pwnboxView').remove()

    If this is your first time pasting something into your DevTools Console, you'll likely see a warning message. This message simply means that you will need to type "allow pasting" in your console for it to allow you to paste the script above.

  5. Press Enter to execute the command.

  6. Refresh the page where your Pwnbox is open in full-screen mode. The page's URL should start with vnc.htb-cloud.com.... Similar to this:

  7. This is how the whole process looks:

    [video-to-gif output image]

Method 3: Using the Address Bar

  1. Navigate to the tab on your browser where you have your section's text content open (this is the tab where you are reading the course – not the one that opens after you make your Pwnbox fullscreen):

  2. Click directly into your browser's URL address bar.

  3. Type the following command exactly as written: javascript:document.getElementById('pwnboxView').remove()

If you are copying and pasting, please note that not always the javascript portion of the above payload will be pasted correctly into your address bar. So, always make sure to check it before pressing Enter.

4. Press Enter to execute the command.

5. Refresh the page where your Pwnbox is open in full-screen mode. The page's URL should start with vnc.htb-cloud.com.... Similar to this:

This is how the whole process looks:

Recording 2026-09-21 at 13.55.44.mp4 [video-to-gif output image]

Once you have executed the command, you can refresh your screen, and the conflicting resizing element will be removed, allowing you to work in full screen without experiencing the VNC resizing issue.

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