CVE-2019-0752 is a type confusion vulnerability in Microsoft Internet Explorer. CISA added it to the Known Exploited Vulnerabilities catalogue on 15 February 2022, which means attackers have used it in real attacks. A remote code execution vulnerability exists in the way that the scripting engine handles objects in memory in Internet Explorer
What a type confusion flaw means in a browser engine
Type confusion vulnerabilities occur when software treats one kind of object as if it were another. In a browser such as Internet Explorer, that mismatch can corrupt memory in the scripting engine and give an attacker a path to execute code inside the browser process.
That matters because browser engines sit at the boundary between untrusted web content and a user’s device. When object handling in memory is wrong, a crafted page can turn what should have been a rendering or scripting error into a security boundary break.
Why this vulnerability class is dangerous in Internet Explorer
Internet Explorer’s scripting engine is a high-value target because it processes complex, attacker-controlled content at scale. A type confusion bug can let malicious script interact with memory in unexpected ways, which is why these flaws are often associated with remote code execution rather than a simple crash.
For defenders, the danger is not just the browser session itself. Successful exploitation can become a stepping stone into the host, especially if the browser is used by a privileged user or if the endpoint still permits legacy browser exposure.
How organisations assess exposure and likely impact
Exposure review starts with basic asset inventory: which endpoints still have Internet Explorer available, where it is enabled for compatibility, and whether users can reach untrusted web content through that path. Vendor advisories and the CISA KEV catalogue are the authoritative places to confirm patch and exploitation status for this CVE.
Because this is a remotely exploitable browser flaw, internet-facing browsing habits matter as much as installed software. A system may be technically patched yet still be operationally exposed if users regularly open untrusted links, visit risky sites, or rely on legacy compatibility modes.
Remediation, detection, and post-exploitation review
The primary remedy is to apply the vendor fix and reduce reliance on Internet Explorer wherever possible. When patching is delayed, limit access to the vulnerable browser, constrain what content can be opened, and use compensating controls that reduce the chance of exploit delivery or execution.
Detection should focus on signs that exploitation may already have occurred, not just whether the patch is installed. Review browser crash telemetry, suspicious child processes, script-related anomalies, and any endpoint behaviour that suggests a memory corruption exploit or post-exploitation payload ran after initial web access.
After remediation, investigate whether the compromise reached beyond the browser. If exploitation succeeded, review the endpoint for downloaded tooling, persistence, unusual outbound connections, and any credentials, sessions, or service identities that may have been exposed during the attack chain.
Risk and Threat Considerations
This flaw is dangerous because it turns ordinary web browsing into a possible code-execution path on a legacy browser engine. Type confusion bugs are especially attractive to attackers when they can be triggered remotely and turned into stable exploitation against widely deployed software.
Failure mechanism: An attacker supplies crafted content that causes the scripting engine to mis-handle an object in memory, which can corrupt execution flow and enable arbitrary code execution in the browser context.
Impact: A successful exploit can lead to malware delivery, endpoint compromise, and follow-on theft or abuse of browser-accessible data and sessions.
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-10 — Information Input Validation | Type confusion arises from unsafe handling of untrusted input and objects. |
| SI-16 — Memory Protection | This CVE is a browser memory corruption issue that can enable code execution. | |
| RA-5 — Vulnerability Monitoring and Scanning | Exposure depends on identifying vulnerable endpoints and confirming patch status. | |
| Recommendation — Validate browser-exposed inputs and object handling to reduce memory corruption exposure. Apply memory-protection controls that limit exploitability of browser-side corruption. Continuously scan assets for Internet Explorer exposure and track remediation. | ||
| CIS Controls v8 | CIS-7 — Continuous Vulnerability Management | KEV-listed exploits require prioritised remediation and exposure tracking. |
| CIS-10 — Malware Defenses | Remote code execution in a browser commonly leads to payload delivery and execution. | |
| Recommendation — Prioritise and remediate KEV-listed browser vulnerabilities across the asset estate. Use layered malware defenses to contain post-exploitation activity after browser compromise. | ||
Practitioner Guidance
Why practitioners should care: Browser engine flaws are often the front door for broader endpoint compromise, so exposure management should treat legacy browser availability as a real attack surface, not a convenience setting.
What to watch for: Prioritise systems that still depend on Internet Explorer for compatibility, because those environments tend to accumulate older content paths, weaker hardening, and higher exposure to drive-by exploitation.
Practitioner takeaway: The safest long-term control is removal of the legacy browser path; until then, reduce exposure, patch quickly, and verify whether any exploitation left evidence on the host.