What happened

CISA added CVE-2010-3962 to the Known Exploited Vulnerabilities (KEV) catalog for Microsoft Internet Explorer, indicating confirmed exploitation in the wild (CVE-2010-3962) CISA KEV. The KEV listing describes an uninitialized memory corruption flaw in Internet Explorer that can enable remote code execution (RCE) when triggered by attacker-controlled content NVD CVE-2010-3962. CISA’s required action is to apply vendor mitigations, follow applicable BOD 22-01 guidance for cloud services, or discontinue use if mitigations are unavailable CISA KEV.

Per the KEV entry, this issue may affect products that are end-of-life or end-of-service, and users should discontinue utilization where mitigations are not available CISA KEV. The CVE record for this issue is maintained by MITRE and documents the vulnerability under the canonical CVE-2010-3962 identifier MITRE CVE-2010-3962. According to the submission data provided, the KEV addition date is 2025-10-06 with a remediation due date of 2025-10-27 for covered agencies CISA KEV.

Why it matters

Inclusion in the KEV catalog signals that reliable exploitation has been observed and that prompt remediation is required by federal civilian agencies under CISA’s directives and timelines CISA KEV. Internet Explorer’s vulnerability is explicitly characterized as enabling RCE via memory corruption, which is a high-impact class of bug for initial access and post-exploitation pivoting NVD CVE-2010-3962. When mitigations aren’t available—especially for potentially EoL/EoS software—CISA directs discontinuation of use, shifting the priority from patching to removal and isolation CISA KEV.

For any environment where IE remains present—even in limited legacy application contexts—the combination of a browser-triggered RCE and known exploitation status materially raises risk, since malicious content can execute code under the user’s context after visiting a crafted or compromised site NVD CVE-2010-3962. Treat KEV-listings as top-tier remediation items; they represent adversary working code in the wild, not theoretical bugs CISA KEV.

Technical detail

CVE-2010-3962 is an uninitialized memory corruption flaw in Microsoft Internet Explorer that an attacker can trigger to achieve remote code execution NVD CVE-2010-3962. The attack vector is remote and typically involves luring a user to a malicious or compromised webpage, where crafted content abuses the memory error to run arbitrary code MITRE CVE-2010-3962. Because the code runs within the context of the current user session, compromise of the browser process translates into the attacker gaining the user’s privileges on the system NVD CVE-2010-3962.

CISA’s KEV entry warns that the impacted product could be end-of-life or end-of-service, a state that typically precludes vendor patch availability and shifts mitigation toward compensating controls or full decommissioning CISA KEV. The KEV program includes only vulnerabilities with evidence of active exploitation, so defenders should assume the existence of operational exploit chains for this bug CISA KEV. The authoritative ID and baseline description are tracked by MITRE, ensuring cross-reference integrity across tools and advisories MITRE CVE-2010-3962.

Defense

• Execute KEV-required actions: apply vendor mitigations where available, or discontinue Internet Explorer use if mitigations are not possible, in line with the KEV directive CISA KEV.
• For entities subject to CISA directives, meet the KEV due date of 2025-10-27 and align with BOD 22-01 guidance for any relevant cloud services or configurations CISA KEV.
• Where removal is non-immediate, quarantine IE from untrusted web content: treat any browsing from IE as a policy violation while you complete migration, consistent with KEV’s discontinue-use posture for unmitigable products CISA KEV.
• Prioritize this item over non-KEV issues in your backlog: KEV entries denote confirmed exploitation, and delayed action widens exposure to RCE from web content CISA KEV. Because exploitation is web-delivered, a single click can hand the attacker code execution in the user session NVD CVE-2010-3962.

Asset owners should also inventory for any residual IE dependencies, plan deprecation, and enforce controls that prevent Internet Explorer from launching during transition windows consistent with CISA’s discontinue-use guidance where no mitigations are available CISA KEV. Treat any observed execution of the vulnerable browser as a high-severity incident until complete removal, given the RCE characteristics described by NVD NVD CVE-2010-3962.

Lyrie Verdict

This is a browser-based RCE with verified in-the-wild exploitation, so human-in-the-loop response is too slow; policy should automatically kill and quarantine any IE execution and block network egress at first sighting, then drive deinstallation on a strict timeline CISA KEV. Because the exploit vector is remote web content and results in arbitrary code in the user context, autonomous controls must treat iexplore.exe launches and outbound connections as immediate containment triggers, not tickets for later review NVD CVE-2010-3962. Align your machine-speed detection and response with KEV priority: if you see IE, stop it, isolate it, remove it—no exceptions while this CVE remains actively exploited CISA KEV.