frame-focusable-content
Web validation
<frame> and <iframe> elements that contain focusable content must not have tabindex="-1".When you assign tabindex="-1" to a <frame> or <iframe>, the browser keeps keyboard focus out of the embedded document. If that frame holds buttons, links, form fields, or any other interactive components, keyboard users cannot reach them. People who are blind, use screen readers, or have limited motor dexterity rely on sequential focus navigation; blocking the focus path traps those users outside content they need.
Pass Patterns
The frame allows focus movement
Removing the negative tabindex lets the browser’s default focus order include the button inside the frame; all users can now reach and operate it.
<iframe
srcdoc="<button>Submit</button>"
title="Payment form">
</iframe>Fail Patterns
The frame blocks focus movement
Because tabindex="-1" removes the frame from the tab sequence, the button inside is unreachable with a keyboard.
<iframe
srcdoc="<button>Submit</button>"
tabindex="-1"
title="Payment form">
</iframe>Try It Yourself
Using a keyboard
- Open the page in a browser.
- Press the Tab key until you get to the
<frame>or<iframe>.
Expected result: The page focus moves to interactive elements within the <frame> / <iframe>.
Actual result: The page focus skips the <frame> / <iframe>, and its content, so keyboard users never get to it.
FAQ
How does this issue relate to 2.1.1 Keyboard?
SC 2.1.1 requires that all functionality be operable via the keyboard. A negative tabindex on a frame prevents keyboard users from reaching interactive elements inside, so it fails this criterion.
Why is this issue marked as Serious?
Blocking keyboard focus from interactive content creates a functional barrier for people who cannot use a pointing device. It affects core tasks across assistive technologies and major browsers, so it needs prompt remediation.
Standards and Regulations
| Standard | Success Criterion | Reference |
|---|---|---|
| WCAG 2.2 | 2.1.1 Keyboard (A) | All functionality of the content is operable through a keyboard interface without requiring specific timings for individual keystrokes, except where the underlying function requires input that depends on the path of the user's movement and not just the endpoints. |
| EN 301 549 | 9.2.1.1 Keyboard | Same as the WCAG text. |
| 508 Trusted Tester | 2.1.1-keyboard-access, 4.A | All functionality can be accessed and executed using only the keyboard. |