CVE-2015-1303

What it actually does

Failure to rethrow cross-context exceptions in V8DOMWrapper allows unhandled exception data to leak across origins, violating Same Origin Policy enforcement for IFRAME content.

Why it matters to the business

Attackers could read or manipulate data belonging to other websites visited by users, resulting in credential theft, session hijacking, or unauthorized actions within the browser.

How an attack unfolds

An attacker serves a crafted HTML page containing a specially constructed IFRAME that triggers a cross-context JavaScript exception; because the rethrow action is omitted, exception details propagate without origin checks, enabling the attacker script to access or influence content from a different origin.

How to fix it

Upgrade Google Chrome to version 45.0.2454.101 or later; ensure automatic updates are enabled and audit any pinned or enterprise-managed deployments for older builds.

How to confirm the fix worked

Verify installed Chrome version is 45.0.2454.101 or newer via chrome://version; test with proof-of-concept HTML containing cross-origin IFRAME exception triggers in a controlled environment to confirm policy enforcement.

Typical attack path

1. Craft malicious HTML document embedding an IFRAME targeting a victim origin
2. Host the document on attacker-controlled site or deliver via phishing/malvertising
3. Victim browser loads the page and executes the IFRAME content
4. Trigger cross-context exception that is not properly rethrown
5. Bypass Same Origin Policy to read or alter cross-origin data

How to detect it

Search web proxy or browser telemetry logs for requests to attacker domains serving IFRAME-heavy pages around the time of suspected exposure; review JavaScript error logs or console output for unexpected cross-origin exception artifacts; no public exploit code or specific IOCs are known.

What your security team should do

• Prioritize update of all Chrome instances to 45.0.2454.101+ within 30 days given stable but non-zero EPSS
• Enable enterprise update policies and monitor for unpatched endpoints via inventory scans
• Review web application code for reliance on IFRAME cross-origin isolation as a control