CVE-2023-37210

What it actually does

A website can intercept full-screen exit attempts by invoking alert and prompt dialogs, trapping the browser in full-screen mode and enabling visual spoofing of trusted interfaces.

Why it matters to the business

Users may be tricked into believing they are interacting with legitimate system prompts or trusted sites, increasing risk of credential theft or social engineering without requiring software installation.

How an attack unfolds

An attacker hosts a malicious page that requests full-screen mode, then repeatedly calls alert or prompt to block the normal exit gesture; the user sees what appears to be a system dialog and may disclose information or perform actions under false pretenses.

How to fix it

Upgrade Mozilla Firefox to version 115 or later; enable automatic updates and verify the installed version meets or exceeds the fixed release.

How to confirm the fix worked

Confirm Firefox reports version 115 or higher in about:support; test full-screen exit behavior on pages that previously triggered the alert/prompt loop.

Typical attack path

1. User visits attacker-controlled site
2. Site requests and enters full-screen via JavaScript
3. Site issues repeated alert/prompt calls on exit attempts
4. User is prevented from leaving full-screen and may interact with spoofed content

How to detect it

Review browser update logs and inventory reports for instances still running versions prior to 115; no reliable post-exploitation artifacts are generated by this client-side issue.

What your security team should do

• Prioritize browser updates across all endpoints within the next patch cycle
• Communicate the update requirement to end users with clear instructions
• Monitor browser telemetry for versions older than 115