How do you patch or mitigate CVE-2017-0037 (Microsoft Edge and Internet Explorer Type Confusion)?

What the fix means for a browser CVE

CVE-2017-0037 is not a configuration weakness you can “tune away” indefinitely. The practical path is to confirm where Microsoft Edge and Internet Explorer still exist, then apply the vendor update or documented mitigation across every affected endpoint and image. If you cannot remediate a system promptly, the safer choice is to remove its internet exposure or retire the product from service.

For browser flaws like this, the real question is usually whether the vulnerable software is still reachable in normal user workflows. Legacy browser binaries, embedded components in older images, and unmanaged endpoints often survive longer than teams expect, so the fix is partly a software task and partly an asset-discovery task.

Because CISA tied this CVE to active exploitation, patching should be treated as an exposure reduction exercise, not a routine maintenance item. That means the browser version, the operating system update path, and the business process that still depends on the browser all matter to the final remediation decision.

How to reduce exposure when patching is delayed

If the update cannot be deployed immediately, the priority is to narrow the attack surface while you work the exception. Remove direct internet use where possible, constrain affected endpoints to only the sites and services they must reach, and avoid leaving the vulnerable browser as a general-purpose entry point for untrusted content.

That mitigation is most effective when paired with a hard inventory of where the product is actually used. In many environments, internet-facing kiosks, shared workstations, and long-lived VDI or image templates are the places where an old browser persists after normal desktops have moved on.

When a mitigation depends on “temporary” containment, document the compensating control and the removal date. Browser exposure that is tolerated without a deadline usually becomes an accepted residual risk rather than a short-term exception.

How to check whether exploitation already happened

After patching or containment, review security and proxy logs for signs of exploitation during the exposure window. For browser vulnerabilities, that means looking for suspicious web content access, unusual download activity, newly created child processes, and any endpoint behaviour that does not fit the user’s normal browsing pattern.

If you find evidence of compromise, treat the browser flaw as an entry point rather than the whole incident. The next step is to determine what the attacker could reach from that session, what credentials or tokens were exposed, and whether the affected endpoint was used to move laterally or stage additional payloads.

That follow-up matters even when the browser has already been updated. A successful exploit can leave behind persistence, downloaded tooling, or stolen session material that survives the patch itself, so “patched” does not automatically mean “clean.”

Risk and Threat Considerations

Browser type-confusion bugs are attractive because they can be triggered through normal web activity and can turn a routine visit into code execution or content parsing abuse. When the browser remains exposed on high-trust endpoints, the vulnerability becomes a foothold for drive-by compromise and post-exploitation activity.

Failure mechanism: The attacker relies on a user or automated process to open hostile content, then abuses the browser parsing flaw to execute code or gain control of the session or endpoint before the defender can intervene.

Impact: The result can be endpoint compromise, theft of browser-stored data or session material, and a starting point for broader network access if the affected machine has privileged reach.

Practitioner Guidance

What to verify: Confirm where Microsoft Edge and Internet Explorer still exist in production, in golden images, and in remote-access or kiosk builds. If you cannot locate the browser version, you do not yet know whether the exposure is gone.

Decision rule: If the vendor update can be deployed, patch first and then validate by rescanning and checking affected endpoints for the vulnerable software state. If patching must wait, remove internet exposure or take the product out of service rather than leaving a known exploitable browser open.

What practitioners underestimate: Legacy browser dependencies often live in templates, remote desktops, and line-of-business workflows, so remediation has to include the operating model, not just the endpoint patch.

Practitioner takeaway: For exploited browser CVEs, the decisive control is fast exposure removal backed by confirmation that the vulnerable browser is no longer reachable in the places users actually work.

Related resources from NHI Mgmt Group

• Guide: Enterprise Browser and Browser Security Guide
• CVE-2017-0037 (Microsoft Edge and Internet Explorer Type Confusion)
• How do you patch or mitigate CVE-2017-0149 (Microsoft Internet Explorer Memory Corruption)?
• How do you patch or mitigate CVE-2010-0249 (Microsoft Internet Explorer Use-After-Free)?
• How do you patch or mitigate CVE-2010-0806 (Microsoft Internet Explorer Use-After-Free)?