Sandboxed iframe can initiate or instantiate downloads. Chrome is planning on removing this capability - i.e. Chrome is going to block all downloads initiated from or instantiated in a sandboxed iframe by default. The embedder may add "allow-downloads" to the sandbox attributes list to opt in. This allows content providers to restrict malicious or abusive downloads.

Motivation

This allows content providers to restrict malicious or abusive downloads.

Documentation

• Spec:
• https://github.com/whatwg/html/pull/4293
• Spec discussions:
• https://github.com/whatwg/html/issues/3236
• Design Doc:
• https://docs.google.com/document/d/1XfLQd9IbJBPAE4IAOvu4EubUaLuICJrDlrmz0Ya_mqQ

Specification

Established standard

Status in Chromium

Blink components: Blink

Removed (tracking bug) in:

• Chrome for desktop release 83
• Chrome for Android release 83

Consensus & Standardization

• Firefox: No signal
• Edge: No signal
• Safari: No signal
• Web Developers: No signals

Owner

• yaoxia@chromium.org

Comments

Downloads can bring security vulnerabilities to a system. Even though additional security checks are done in Chrome and the operating system, we feel blocking downloads in sandboxed iframes also fits the general thought behind the sandbox.

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Last updated on 2021-01-04