CVE-2023-6210

What it actually does

The vulnerability permits a pop-up created from a javascript: URL on an HTTPS page to load blockable insecure HTTP content such as iframes, bypassing mixed-content restrictions.

Why it matters to the business

Attackers could load malicious or unauthorized content into otherwise secure browsing sessions, increasing risk of data exposure or unauthorized actions across user populations.

How an attack unfolds

An attacker hosts a malicious HTTPS page that triggers a javascript: pop-up; the pop-up then loads HTTP-sourced iframes or scripts that would normally be blocked, allowing unauthorized content execution.

How to fix it

Upgrade Mozilla Firefox to version 120 or later.

How to confirm the fix worked

Confirm installed Firefox version is 120 or higher; test that javascript: pop-ups from HTTPS pages no longer load HTTP blockable resources.

Typical attack path

1. Host a malicious HTTPS webpage
2. Trigger a javascript: URL pop-up from that page
3. Load blockable HTTP content such as iframes inside the pop-up
4. Execute scripts or exfiltrate data via the unauthorized content

How to detect it

Inspect browser history and mixed-content logs for javascript: initiated pop-ups that loaded HTTP resources; correlate with web traffic showing unexpected insecure loads from secure origins.

What your security team should do

• Upgrade all Firefox deployments to version 120 or newer immediately
• Enforce browser update policies across the environment
• Review web proxy or endpoint logs for mixed-content patterns