Is CVE-2020-0674 (Microsoft Internet Explorer Scripting Engine Memory Corruption) being exploited in the wild?

By NHI Mgmt Group Editorial Team Updated October 19, 2026 Domain: Threats, Abuse & Incident Response

Yes. CISA added CVE-2020-0674 to its Known Exploited Vulnerabilities catalogue on 3 November 2021, which it does only when there is reliable evidence of active exploitation. CISA has not linked it to known ransomware campaigns. Microsoft Internet Explorer contains a memory corruption vulnerability due to the way the Scripting Engine handles objects in memory. Any organisation running the affected product should treat remediation as urgent.

What “being exploited in the wild” means for CVE-2020-0674

CISA’s KEV listing is the practical signal that matters here: if a vulnerability is in KEV, defenders should assume real-world exploitation is already occurring and prioritise it ahead of ordinary backlog work. For CVE-2020-0674, the issue is not abstract exposure, it is an active exploitation problem that should move remediation into urgent change management.

The most important question for practitioners is not whether the vulnerability exists, but whether any instance of Microsoft Internet Explorer and its Scripting Engine remains reachable in the environment. Even where IE is not the primary browser, legacy dependencies, compatibility modes, embedded controls, or older endpoints can keep the attack surface alive long after users think it is gone.

Because the flaw is a memory corruption issue in scripting-engine object handling, exposure is usually tied to content processing in the browser context. That makes internet-facing user workstations, shared desktop estates, and any environment that still depends on legacy browser behaviour the first places to confirm.

How to confirm exposure and decide on remediation priority

Start by identifying whether Internet Explorer is still enabled or callable anywhere in the estate, including managed desktops, remote access hosts, virtual desktop pools, and systems that use IE-based components for internal applications. If the browser or its engine is still present, treat the asset as potentially exposed until you can prove otherwise.

Next, check whether the vulnerable surface can actually be reached by users or automated workflows. A system that still has IE installed but is effectively isolated from untrusted content is a different operational risk from one where users can browse external pages or open untrusted HTML in day-to-day work.

For prioritisation, focus first on systems that are externally reachable, user-interactive, or mission-critical. The practical logic is simple: once a CVE is known to be exploited in the wild, confirmed exposure plus user interaction is enough to justify urgent remediation even before you have evidence of compromise.

What to do if patching or removal has to wait

If immediate patching is blocked, reduce the attack surface rather than waiting for a perfect fix. Disable or restrict Internet Explorer wherever business use allows, remove unnecessary browser dependencies, and use application controls or browser policies to prevent untrusted content from reaching legacy components.

Where IE remains necessary for a limited business process, narrow access to the smallest possible user group and isolate those systems from general browsing. In practice, that means treating the legacy dependency as an exception with explicit ownership, compensating controls, and a short remediation deadline.

It is also worth reviewing whether the same business function can be moved to a modern browser path or a supported application interface. A temporary containment measure is useful, but long-lived reliance on a known exploited browser component creates recurring risk that will keep returning to the queue.

Risk and Threat Considerations

Actively exploited browser memory-corruption flaws are attractive because they can turn normal user activity into code execution or a foothold on the endpoint. Once an attacker gets that foothold, the browser is often only the entry point, not the final objective.

Failure mechanism: A malicious page or content path triggers the Scripting Engine flaw during object handling, causing corruption that can be shaped into execution or crash behaviour. That makes the vulnerability useful for initial compromise when users can be lured to malicious or compromised content.

Impact: Successful exploitation can expose the endpoint to full user-context compromise, follow-on payload delivery, and potential lateral movement if the affected device has access to sensitive internal resources.

Standards & Framework Alignment

This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.

MITRE ATT&CK addresses the attack and risk surface, while CIS Controls v8, NIST CSF 2.0, NIST SP 800-53 Rev 5 and OWASP ASVS set the governance and control requirements practitioners need to meet.

Framework	Control / Reference	Relevance
CIS Controls v8	CIS-7 — Continuous Vulnerability Management	The subject is a known exploited vulnerability requiring urgent prioritization and remediation.
Recommendation — Prioritize and remediate the KEV-listed browser flaw through continuous vulnerability management.
NIST CSF 2.0	ID.RA-01 — Asset Vulnerabilities Are Identified and Documented	Exposure confirmation depends on identifying systems still reachable by the vulnerable browser engine.
Recommendation — Identify affected endpoints and document the vulnerable Internet Explorer exposure.
NIST SP 800-53 Rev 5	SI-2 — Flaw Remediation	The CVE requires prompt remediation or compensating containment when patching is delayed.
Recommendation — Remediate the flaw promptly or apply compensating controls until remediation is complete.
OWASP ASVS	V12 — Secure Communication	Browser exploitation paths often depend on unsafe content delivery and untrusted web interactions.
Recommendation — Restrict untrusted content paths and harden browser-facing communication channels.
MITRE ATT&CK	T1203 — Exploitation for Client Execution	This memory-corruption browser issue is an exploit path that can execute code in a client context.
Recommendation — Detect and block exploitation-for-client-execution activity on browser endpoints.

Practitioner Guidance

What to verify: Confirm whether Internet Explorer is disabled, still callable, or only present for legacy compatibility. The key operational test is not “is the browser installed,” but “can an untrusted page still reach the vulnerable engine on a real user path?”

What to prioritise: Patch or remove the exposure on internet-facing and high-use endpoints first, then move to less exposed legacy systems. If you have a vulnerability backlog, KEV-listed browser flaws should be handled ahead of lower-confidence, non-exploited items.

Escalation / exception: If remediation cannot happen immediately, treat the system as an exception with compensating controls, explicit owner sign-off, and a short expiry. Long-lived exceptions are especially dangerous for browser vulnerabilities because user behaviour can reintroduce exposure at any time.

Practitioner takeaway: For a KEV-listed browser memory-corruption issue, the decision point is exposure, not curiosity, if IE can still be invoked on a reachable endpoint, the right response is urgent containment and removal, followed by verification that the legacy path is truly gone.

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NHIMG Editorial Note
Reviewed and updated by the NHIMG editorial team on October 19, 2026.
NHI Mgmt Group — the #1 independent authority on Non-Human Identity, IAM, and Agentic AI security. nhimg.org