CVE-2017-0037 is a type confusion vulnerability in Microsoft Edge and Internet Explorer. CISA added it to the Known Exploited Vulnerabilities catalogue on 28 March 2022, which means attackers have used it in real attacks. Microsoft Edge and Internet Explorer have a type confusion vulnerability in mshtml.dll, which allows remote code execution.
How this vulnerability class behaves
Type confusion is dangerous because code begins treating one kind of object as another, which can corrupt memory, bypass expected logic, and turn a parsing bug into remote code execution. In browser components such as the CVE Program ecosystem, that kind of flaw is especially serious because the browser processes untrusted web content at scale.
In practice, the attack surface is not just the browser UI, but the underlying rendering and script execution engine. When the vulnerable component is shared across multiple products, a single defect can expose a wide user base to drive-by exploitation and code execution from malicious web content.
Why this is dangerous in Microsoft Edge and Internet Explorer
This CVE affects Microsoft Edge and Internet Explorer, and the primary danger is that a malformed page or content chain can trigger unsafe memory handling inside the browser engine. Once an attacker reaches remote code execution, the browser stops being just a client application and becomes an entry point into the endpoint.
Because browser exploitation often happens before any user notices a problem, the impact can include malware delivery, credential theft, and follow-on activity using the victim session. For general vulnerability reference data and product record context, organisations should check the NIST National Vulnerability Database alongside the vendor advisory and the CISA KEV catalogue.
How organisations check exposure and reduce risk
Exposure review starts with knowing where the affected browser and underlying engine are present, including unmanaged endpoints, legacy systems, virtual desktops, and any internet-facing user groups. Asset inventory matters because browser vulnerabilities are often more widespread than teams expect, especially where multiple Windows builds, compatibility modes, or older application dependencies are involved.
When patching cannot happen immediately, organisations should reduce exposure by restricting access to untrusted content, hardening browser configuration, limiting privileged browsing, and monitoring whether the affected software is still permitted in the environment. For a broader remediation workflow, the Vulnerability Management Guide is useful for prioritisation, exception handling, and verification.
Detection, post-exploitation review, and recovery
Browser exploitation often leaves indirect evidence rather than a clean signature, so detection should combine endpoint telemetry, browser crash or script anomaly review, suspicious child-process analysis, and network inspection for unusual follow-on traffic. If exploitation is suspected, treat the endpoint as potentially compromised, not merely patched.
Post-patch review should look for dropped binaries, persistence mechanisms, unusual downloads, browser session abuse, and any lateral movement that may have started from the initial web execution. If the browser session carried access to email, portals, password managers, or internal admin tools, rotate exposed credentials and invalidate active sessions where appropriate.
Risk and Threat Considerations
Browser type confusion is a classic attacker-friendly bug class because it can convert ordinary web browsing into code execution without requiring a separate software install. The practical risk is highest when users browse untrusted content, when patching lags behind public exploitation, or when the browser sits close to high-value credentials and corporate applications.
Failure mechanism: The attacker supplies content that drives the engine into misinterpreting an object type, causing memory corruption and allowing code execution in the browser process.
Impact: Successful exploitation can lead to malware deployment, session theft, data access, or additional compromise from the affected endpoint.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
NIST SP 800-53 Rev 5 and CIS Controls v8 set the governance and control requirements practitioners need to meet.
| Framework | Control / Reference | Relevance |
|---|---|---|
| NIST SP 800-53 Rev 5 | SI-2 — Flaw Remediation | CVE exploitation risk requires timely remediation of known software flaws. |
| SI-4 — System Monitoring | Detection of browser exploitation depends on monitoring for abnormal execution and follow-on activity. | |
| RA-5 — Vulnerability Monitoring and Scanning | Exposure checks for a KEV-listed CVE require asset visibility and vulnerability assessment. | |
| Recommendation — Track and remediate the browser flaw quickly, and verify closure after patching. Monitor browser and endpoint activity for signs of exploitation and post-exploit behavior. Continuously scan assets to confirm where the vulnerable browser remains deployed. | ||
| CIS Controls v8 | CIS-7 — Continuous Vulnerability Management | This CVE should be prioritized through asset discovery, vuln scanning, and remediation tracking. |
| CIS-10 — Malware Defenses | Browser RCE can deliver malware, so preventative and detection controls matter after exploitation. | |
| Recommendation — Prioritise and remediate the vulnerable browser across all in-scope assets. Use malware defenses to reduce payload delivery and detect malicious follow-on activity. | ||
Practitioner Guidance
What to watch for: Prioritise any endpoint that still runs the affected browser family, especially if it has internet exposure or is used by privileged users. If the issue cannot be remediated immediately, treat compensating controls as temporary only and keep them narrow and time-bound.
Governance implication: Browser vulnerabilities like this should be managed as asset and exposure problems, not just patch tickets. Ownership needs to cover endpoint inventory, browser lifecycle, exception approval, and post-exploitation validation.