CVE-2018-0824 (Microsoft COM for Windows Deserialization of Untrusted Data)

What makes this vulnerability dangerous in Windows COM

COM deserialization flaws are dangerous because they can let untrusted data be interpreted as executable object state. In Windows environments, that can turn a parsing bug into code execution, privilege abuse, or a foothold for broader system compromise, especially where the vulnerable component is exposed to routine user or application activity.

Because this CVE is in Microsoft Windows and is publicly listed in CISA’s KEV catalogue, it should be treated as an actively exploited weakness rather than a theoretical bug. The practical lesson is that seemingly ordinary serialization paths can become high-value attack surfaces when attackers can influence the data being processed.

How organisations assess exposure

Exposure checks should start with a current asset inventory, then narrow to Windows hosts that run the affected product and any systems that can receive attacker-controlled input from users, services, or nearby applications. For KEV-listed issues, inventory alone is not enough, organisations also need to know which endpoints are internet-facing, which are high-value, and which business units still rely on the vulnerable component.

Vendor advisories remain the authoritative source for affected versions and fix details, while the CVE Program and the NIST National Vulnerability Database help teams confirm identifiers, descriptions, and record metadata. For prioritisation, a vulnerability management guide is useful when mapping KEV status to patch queues, remediation SLAs, and exception handling.

Remediation and compensating controls

The preferred response is to apply the vendor fix as soon as operationally possible, because KEV inclusion indicates the vulnerability is already known to be exploited in the wild. Where immediate patching is not possible, reduce the reachable attack surface by limiting exposure, tightening access to the affected systems, and applying any vendor-recommended mitigation exactly as documented.

Compensating controls matter most when patch windows are delayed by change freezes, legacy dependencies, or critical uptime requirements. In those cases, organisations should treat the issue as a temporary trust problem: if the vulnerable component can still process attacker-controlled data, the residual risk remains until the fix is in place.

Detection and compromise review

For an exploited deserialization flaw, detection should focus on signs that the vulnerable Windows host executed unexpected code, spawned unusual child processes, or made suspicious follow-on connections after the initial trigger. If the host was reachable from untrusted users or networks, review whether the compromise may have been used to stage additional payloads or move laterally.

After patching, organisations should still review the system for post-exploitation activity, because fixing the flaw does not undo prior compromise. If attackers gained execution through the vulnerability, credential theft, persistence mechanisms, scheduled tasks, and changes to security tooling may all survive the patch and require separate cleanup.

Risk and Threat Considerations

KEV-listed Windows vulnerabilities are attractive because they often combine broad reach with a reliable exploitation path and a high operational payoff. Deserialization bugs are especially risky when attackers can feed crafted data into a trusted parser, because the trust boundary is crossed before normal application logic has a chance to validate the content.

Failure mechanism: An attacker supplies malicious serialized data to the COM component, causing the Windows process to interpret it in an unsafe way and execute attacker-influenced code or actions.

Impact: Successful exploitation can lead to system compromise, persistence, lateral movement, or the theft of credentials and other sensitive secrets from the affected host.

Practitioner Guidance

Why practitioners should care: When a Windows flaw is already in KEV, remediation priority should be driven by exposure and exploit activity, not by local convenience or patch backlog order. Teams should assume the vulnerable path is likely to be probed quickly and repeatedly.

Practitioner takeaway: Treat this as a time-sensitive exploitation risk, not a routine maintenance item, and verify both remediation and evidence of compromise before closing the case.

Related resources from NHI Mgmt Group

• CVE-2025-59287 (Microsoft Windows Server Update Service (WSUS) Deserialization of Untrusted Data)
• CVE-2023-21529 (Microsoft Exchange Server Deserialization of Untrusted Data)
• CVE-2025-53770 (Microsoft SharePoint Deserialization of Untrusted Data)
• CVE-2026-20131 (Cisco Secure Firewall Management Center (FMC) Software and Cisco Security Cloud Control (SCC) Firewall Management Deserialization of Untrusted Data)