Yes. CISA added CVE-2017-0149 to its Known Exploited Vulnerabilities catalogue on 24 May 2022, 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 that allows remote attackers to execute code or cause a denial-of-service (DoS) via a crafted website.
How to confirm whether CVE-2017-0149 was actively exploited
CISA’s KEV listing is the fastest practical confirmation that the vulnerability is not just theoretical. If a CVE appears there, treat it as evidence of active exploitation and use the vendor advisory plus the KEV entry to confirm the product, the attack surface, and the required remediation path.
For browser-era vulnerabilities like this one, the right question is not only whether a patch exists, but whether exposed systems still permit the vulnerable component to be used. Internet-facing endpoints, legacy desktops, kiosk systems, and any environment that still permits Internet Explorer usage deserve immediate exposure review.
When you assess exposure, focus on the specific combination of software presence, user reachability, and residual browser use. If Internet Explorer is still enabled anywhere, the practical risk is that a crafted page can reach the vulnerable code path even if the browser is not the organisation’s primary browser anymore.
What the vulnerability means operationally
The issue is a memory corruption flaw in Microsoft Internet Explorer, which means the failure mode is code execution or denial of service after malicious content is rendered. That makes it more than a nuisance bug, because exploitation can become an initial access path if users can be driven to a malicious site or a compromised page.
For defenders, the important distinction is that browser vulnerabilities often bypass perimeter assumptions. Security teams cannot rely on network filtering alone if users can still browse arbitrary web content from exposed systems. Browser hardening and application control matter here because they reduce the chance that the vulnerable path is reachable in day-to-day use.
The most useful operational response is to pair remediation with exposure reduction. Where Internet Explorer is still present, confirm whether it is actually required, whether it can be disabled, and whether any business workflow still depends on it. If it must remain, isolate it as tightly as possible and reduce the set of users and hosts that can invoke it.
What to do when patching or removal is delayed
When immediate remediation is not possible, treat the vulnerability as an active attack surface and reduce opportunities for exploitation rather than waiting for proof of compromise. Block unnecessary web access from affected hosts, constrain who can launch the browser, and monitor for suspicious child processes, unexpected script activity, and repeated crashes tied to browser rendering.
For a legacy browser flaw, compensating controls should be about reachability and blast radius. If the vulnerable application cannot be removed quickly, move the affected systems out of high-trust zones, strip local admin rights where possible, and review whether endpoint protections are tuned to detect exploit delivery rather than only known malware signatures.
After remediation, validate that the vulnerable browser path is no longer available in practice, not just in policy. A configuration change that leaves a dormant executable reachable, or a fallback compatibility mode that still exposes the code path, can preserve the risk even after a patch cycle is declared complete.
Risk and Threat Considerations
Internet Explorer exploitation matters because web content is a common delivery path and memory corruption can convert a routine browsing action into code execution. That makes the vulnerability attractive for opportunistic exploitation, especially where legacy browser support remains enabled on older or poorly governed endpoints.
Failure mechanism: A crafted website or maliciously controlled page content triggers memory corruption in the browser engine, allowing remote code execution or a denial-of-service condition on the victim system.
Impact: Successful exploitation can lead to device compromise, user session abuse, follow-on malware delivery, or service interruption, especially if the browser is still permitted on systems with broad network or user privilege.
Standards & Framework Alignment
This section maps relevant standards and security frameworks to the operational risks and controls described in this guidance.
CIS Controls v8, NIST SP 800-53 Rev 5 and NIST CSF 2.0 set the technical controls, while ISO/IEC 27001:2022 defines the regulatory obligations.
| Framework | Control / Reference | Relevance |
|---|---|---|
| CIS Controls v8 | CIS-7 — Continuous Vulnerability Management | Active exploitation and KEV-driven triage are core vulnerability-management decisions. |
| Recommendation — Prioritise KEV-listed browser flaws for rapid remediation and exposure reduction. | ||
| NIST SP 800-53 Rev 5 | SI-2 — Flaw Remediation | This CVE requires timely remediation and validation of vulnerable software removal. |
| SI-3 — Malicious Code Protection | Web-delivered exploitation makes content filtering and exploit protection relevant. | |
| Recommendation — Track, remediate, and verify the browser flaw is no longer reachable. Use layered content and exploit protections to reduce drive-by exploitation risk. | ||
| ISO/IEC 27001:2022 | A.8.8 — Management of technical vulnerabilities | The issue is a technical vulnerability requiring prioritised handling and verification. |
| Recommendation — Register, prioritise, and remediate the vulnerability under technical-vulnerability management. | ||
| NIST CSF 2.0 | DE.CM-08 — Monitoring for anomalous activity is performed | Exploit attempts against browsers warrant monitoring for suspicious execution and crashes. |
| Recommendation — Monitor affected endpoints for exploit indicators and abnormal browser behavior. | ||
Practitioner Guidance
What to verify: Confirm where Internet Explorer is still installed, enabled, or callable through compatibility settings. In many environments the real exposure is not the default browser, but a hidden legacy path left available for a subset of users or applications.
Decision rule: If the vulnerable browser can still reach untrusted web content, treat the issue as an active exposure problem, not just a patching task. Prioritise removal or hard disablement before you spend time on lower-value tuning.
Practitioner takeaway: For exploited browser CVEs, the key control is reducing reachability as much as applying the fix, because a patched but still-enabled legacy browser can remain a practical attack path.
Related resources from NHI Mgmt Group
- Guide: Enterprise Browser and Browser Security Guide
- Is CVE-2010-3962 (Microsoft Internet Explorer Uninitialized Memory Corruption) being exploited in the wild?
- Is CVE-2013-3163 (Microsoft Internet Explorer Memory Corruption) being exploited in the wild?
- How do you patch or mitigate CVE-2017-0149 (Microsoft Internet Explorer Memory Corruption)?
- Is CVE-2015-2502 (Microsoft Internet Explorer Memory Corruption) being exploited in the wild?
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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