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CVE-2026-56178

MEDIUM

Time-of-check time-of-use (toctou) race condition in Microsoft Defender for Endpoint allows an authorized attacker to elevate privileges locally.

Published
Jul 14, 2026
Updated
Jul 22, 2026
Affected
0 pkgs
Patched
None yet
Exploits
None indexed

Description

Time-of-check time-of-use (toctou) race condition in Microsoft Defender for Endpoint allows an authorized attacker to elevate privileges locally.

Affected Products

1 product · 1 configurations
Application
defender for endpointmicrosoft
≥ 101.0.0 && < 101.26042.0020
range

Detection & mitigation playbook

Vendor / appliance
  1. Detect

    Inventory every microsoft defender for endpoint deployment and check each version against the affected-products list above. Because the exploit targets the running system rather than your application code, also watch for exploitation at the network and runtime layer — O3 flags the exploit behaviour from runtime telemetry and egress traffic even before a vulnerable build is confirmed.

  2. Fix

    Apply the microsoft defender for endpoint security patch or hotfix for CVE-2026-56178 on the affected version, following the vendor advisory for your exact build.

  3. Workarounds

    Cut exposure now: restrict the management/admin interface to trusted networks, segment the device, and apply the vendor's recommended configuration mitigations and any WAF/IPS signature. O3's runtime protection blocks the exploit chain at execution, holding the line on unpatched or end-of-life systems until you can patch.

  4. How O3 protects you

    O3 detects and blocks CVE-2026-56178 exploitation at runtime: eBPF exploit-chain detection, plus L7 egress monitoring that catches the post-exploitation callback and severs the attacker's outbound channel.

Tailored to CVE-2026-56178. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Time-of-check time-of-use (toctou) race condition in Microsoft Defender for Endpoint allows an authorized attacker to elevate privileges locally.
O3 Security · Runtime Protection

Is CVE-2026-56178 being exploited in your environment?

O3's eBPF runtime sensors and L7 egress monitoring detect and block the CVE-2026-56178 exploit chain at execution — protecting unpatched and end-of-life systems until the vendor patch is applied.

CVE-2026-56178: Defender For Endpoint CWE-367 (Medium 5.5) | O3 Security