Steps to reproduce:

1. Enable the PdfExportFilter filter
2. Open the page with RadEditor in the browser
3. Insert a table element
4. Select the Table in the Node Inspector and apply a width of 500px
5. Switch to HTML mode and you'll notice that the width attribute/inline style has gone

Dear support,

we've recently updated to the Telerik version 2025.4.1210.462 and are experiencing issues with the (relatively) new RadEditor filter EditorFilters.StripCssExpressions. In particular, setting the RadEditor.Content and rendering the RadEditor object drastically tanks performance in certain situations.

We're aware of the web.config setting to increase the Telerik.RegexMatchTimeout, but for a 79KiB content to be rendered basically instantaneously with the previously mentioned filter being explicitly disabled to take 23+ seconds to render if the filter is enabled is quite shocking to me.

Please find a simple sample page (including the content-value) attached.

We'd really like to use the new security features of the RadEditor, but given this performance impact, we'll be unable to ship this feature as-is.

(Off-topic: We're currently evaluating to re-enable the EditorFilters.StripJavaScriptUris which removed our base64-encoded images in the November release of Telerik, but got fixed with the December release.)

Thanks in advance for investigating this issue and I'll be awaiting your feedback.

Kind regards

Hi, 

We need to add an aria-label attribute to the RadEditor toolbar link buttons to match the title attribute text. I have been successful using JQuery on other controls to improve accessibility, but this one is not working. It appears because the link button is not rendered since is a pseudo element using the ::before. I have been unable to inject the attribute on page load. 

The issue is for screen readers the editor buttons are not announced when using the arrow key navigation which is called virtual mode. The buttons do announce when using the tab key which is called forms mode.

If this can be a bug fix it would benefit everyone, otherwise, if you have a code suggestions that is helpful. Image attached. 

Thank you.

The newly introduced StripJavaScriptUris security filter is incorrectly identifying and removing legitimate base64-encoded image data URIs (e.g., data:image/png;base64,...) from RadEditor content. The filter treats these safe image URIs as potential XSS threats and strips them along with dangerous JavaScript URIs.

1. In Design mode, select all text (Ctrl + A) and delete it.
2. Switch to HTML mode.
3. Switch back to Design mode.
4. Press Ctrl + Z (Undo).

• The first Ctrl + Z has no effect; the deleted text is restored only after pressing Ctrl + Z a second time.

Steps to Reproduce

1. Open a page containing RadEditor with some content in it
2. In Design mode, select all text (Ctrl+A)
3. Delete the selected text
4. Switch to HTML mode
5. Switch back to Design mode
6. Press Ctrl+Z (Undo) a couple of times.
   

Current Result

• A JavaScript error is thrown in the browser console
• The undo operation fails to restore the deleted content
• Error occurs in _updateBrowserRangeStart method when calling this.range.setStart(e, t)

Expected Result

• The undo operation should work without errors
• The previously deleted text should be restored
• No JavaScript errors should appear in the console

When using RadEditor with the StripDomEventAttributes content filter enabled, script execution can still occur when switching from HTML to Design mode.

Certain HTML and SVG elements containing attributes such as onload, onclick, or href/to values that start with javascript: are not fully sanitized before the editor’s content is rendered in Design view. As a result, embedded script code can run during the mode transition even though the anti-script filter is active.

Reproduction steps:

Add a RadEditor with the default filters:

<telerik:RadEditor runat="server" ID="RadEditor1"
    ContentFilters="DefaultFilters,StripDomEventAttributes">
</telerik:RadEditor>

1. Load the page.
2. Switch the editor to HTML mode.
3. Paste any of the following samples (look below)
4. Switch to Design view
5. Watch alerts

<svg/onload=alert(1)><svg>
<svg
onload=alert(1)><svg> # newline char
<svg	onload=alert(1)><svg> # tab char
<svgonload=alert(1)><svg> # new page char (0xc)

 

 

 

When we edit the widget > click on the table on a random cell > select Table Properties > The table wizard will always default to the top left cell > This is working as expected.
If you click in the table (not the editor) and select Cell Properties > the wizard will display (highlight) the cell you selected in the table is it expected that when selecting table properties it always default to the left side first box but when selecting cell properties it will show the current cell which we are in.

video link:- https://jam.dev/c/c1cdf56c-53ab-4218-8774-65907b3efd6d 

When loading RadEditor (Telerik UI for ASP.NET AJAX 2025 Q2) in Internet Explorer 10/11 or Edge in IE Compatibility Mode, the editor does not render and JavaScript errors occur immediately upon page load.

SCRIPT1002: Syntax error
SCRIPT5022: Sys.ArgumentUndefinedException: Value cannot be undefined. Parameter name: type

Hi,

We are using Material Theme in our application. We see the problem in Rad Editor's Ribbon. Some icons are overlapping the Text. In the demo, it seems to be same behavior.

Regards,
Jamil

Hi 

I have a RadEditor control where some toolbar functionalities are not working.

After searching for a possible reason, I used the OnClientCommandExecuting client-side event and noticed that sometimes, instead of the args with its value, I found the item of a RadTreeList control present on the page.

I tried to reproduce the issue by inserting an Editor and a TreeList on a page. I write some text in the Editor and try to change the color or background. Not always (and I can't figure out when), but sometimes the args are incorrect.

For example, if I open a node of the tree, the error is almost certain after that.

I send you an image of my javascript debugger.

I don't know what I can do, do you have any ideas?

Thanks

Michela

I am experiencing an issue in the Telerik Rad Editor where, after copying and pasting a long sentence in a single line, if I apply bold formatting to a word and place the cursor at the beginning of the bolded word, pressing Enter results in an empty line being inserted between the text. This behavior is reproducible on the Telerik webforms editor demo site as well.

I would appreciate any guidance on how to resolve this issue. Thanks in advance.

When I want to clear a class in the RadEditor the class is cleared in the hyperlink manager, but not in the area in the footer of the RadEditor.

If 'clear class' is selected nothing happens.

When using Metro skin, if I click on a disabled button (Undo, Redo, Unlink and so on), its icon disappears until I click outside it.

https://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx?skin=Metro

This does not happen with MetroTouch, Silk or Default skin. How do I replicate the same behavior with Metro skin?

Uncaught TypeError: Failed to execute 'createObjectURL' on 'URL': Overload resolution failed error is thrown when pasting an image or a chart image from MS Word in RadEditor in Chrome / MS Edge.

The problem can be reproduced in the live demos too: https://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx. 

The error also prevents the execution of the OnClientPasteHtml event of the control.

 

Whether the editor has content, or has no content, the XHTML validator always gives the same errors as per the attached screenshot.

https://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx 
https://demos.telerik.com/aspnet-ajax/editor/examples/built-in-dialogs/defaultcs.aspx   

The XHTML validator in the editor control is not working.

As per attached screenshot, when you click it and opens the window it simply states the following.

"Sorry! This document cannot be checked."

"Sorry, this type of URL scheme (undefined) is not supported by this service. Please check that you entered the URL correctly"

Can someone tell me why this is happening? It's also broken on the editor demos on your site. Maybe something on the W3C validator has changed making it no longer compatible/viable?

https://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx

https://demos.telerik.com/aspnet-ajax/editor/examples/built-in-dialogs/defaultcs.aspx 

In earlier versions of the editor, the css class was applied to the image tag itself, which is the correct way to do it. Otherwise the applied css class has no effect on the image.

The editor does not work at all in Chrome for iOS.

You can reproduce it in this demo:

https://demos.telerik.com/aspnet-ajax/editor/examples/overview/defaultcs.aspx

 

 

 

Using the latest 2022.3.1109.45, our web application is catching "Invalid Resource Request" exceptions when the Windows7 or Vista (maybe others too) loads the "Editor" control in "Classic" mode.    By decoding the URL, the control is having problems locating the image below

WebResource.axd?d=ZHkUja8e5EF7zNoz8IiY_kAGH7MBQgCnq0BEYT2AtFLv57GDfGbEymwRG8H68WuiE_6l2fpZpqb_FzVc_OItknX-LMTzvQOwC0Mk8HaCtGvNzWl-5nNlZ6xpbOjNSk4A0QtPGtyV0UA-BWX4bOfPU8EI30eAVg8UO6p7yERiuEbCUoiZOGUevYGPdrNVvPel0&t=638034624000000000
Error Message: This is an invalid webresource request.

Telerik.Web.UI.Skins|Telerik.Web.UI.Skins.Vista.Editor.ToolbarVerticalSprites.gif

Telerik.Web.UI.Skins|Telerik.Web.UI.Skins.Windows7.Editor.ToolbarSprites.gif

Change the skin of the radeditor in the default.aspx to another skin such as "metro" and the problem will not happen.    It works OK at least on Black, Metro and Silk but haven't tested others, you can tell it doesn't work when the divider bars in the editor toolbar don't appear properly.