CVE-2021-26414: Windows DCOM Server security feature bypass

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 20 September 2026. Confidence: low.

medium priorityCVSS rates it medium (4.8) with high integrity impact but high attack complexity and required user interaction, and it is not in KEV, though the high EPSS score and broad affected product list argue against deprioritizing it.

What it is

CVE-2021-26414 is a security feature bypass in the Windows DCOM Server. The record gives only a one-line description and no root-cause detail, so the exact mechanism is not documented here. It matters because a bypass of a security feature can let an attacker evade a control that defenders rely on, and the affected product list spans Windows client and server releases from Windows 7 through Server 2022.

Impact

An attacker gains the ability to bypass a Windows DCOM Server security feature; the CVSS vector shows high integrity impact with no confidentiality or availability impact. No further impact detail is provided in the record.

Attack surface

The vector is network-reachable (AV:N) but requires low privileges (PR:L) and user interaction (UI:R), so an attacker needs a foothold and must induce a user action. No specific interface, protocol or component is named in the description.

Exploitation

Not listed in CISA KEV and no ransomware use is documented; EPSS is high at roughly 0.50 probability (98.8th percentile), but the references are only a vendor patch advisory and a third-party advisory, with no public exploit tag.

What to do

• Apply the Microsoft security update referenced in the vendor advisory for CVE-2021-26414 across all affected Windows client and server versions.
• Inventory Windows 7, 8.1, RT 8.1, 10, Server 2008, 2012, 2016, 2019 and 2022 hosts and confirm patch status, prioritizing internet-facing and domain-controller systems.
• Restrict DCOM/RPC exposure at network boundaries and between segments, allowing only required hosts and ports.
• Limit interactive logon and local privilege on endpoints so the PR:L and UI:R preconditions are harder to satisfy.
• Monitor the vendor advisory for any follow-up guidance or configuration changes tied to this bypass.

Detection

• Alert on unexpected DCOM/RPC traffic between workstations or across network segments, especially to hosts that do not normally serve DCOM.
• Correlate low-privileged process activity with subsequent DCOM object activation or security-feature configuration changes on the same host.
• Hunt for tampering with DCOM-related registry keys or security settings outside change windows.
• Review endpoint telemetry for user-driven execution chains that precede DCOM activity, since the vector requires user interaction.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.