CVE-2026-69874

Think of Windows ALPC as an internal messaging system used by parts of Windows to talk to each other. This flaw is like a “trap door” where a local attacker who already has legitimate ability to run code can trigger the system to incorrectly use an unsafe pointer, leading to getting higher privileges. That can let an attacker do more than they should on the same machine.

This matters if you run Windows 10, Windows 11, or Windows Server 2019/2022/2025 on endpoints or servers where an attacker could already be “authorized” to run code (for example, through a compromised account or legitimate access). Because the weakness requires an attacker to already have a local foothold/ability to act on the machine, it is not primarily a remote-from-the-internet issue. Patch risk is highest on systems where untrusted or semi-trusted people/apps can run code locally (or where accounts may be compromised).

This is rated RED because it can turn a local, already-authorized attacker into a higher-privilege attacker on the machine. Even though there is no public exploit code on record and it is not listed in CISA KEV, the bug class (local privilege escalation) is exactly the kind attackers aim for after gaining initial access. Patch on a fast timeline for any affected hosts you cannot strongly restrict from local code execution by untrusted parties.

1. Inventory and confirm exposure

   • Identify every endpoint and server running one of: Windows 10, Windows 11, Windows Server 2019, Windows Server 2022, Windows Server 2025.
   • For each device, record the exact Windows build number (the 10.0.xxxx.yyyy form).

2. Compare against fixed versions
   Patch any device that is on an affected build to at least one of the following fixed versions:

   • Windows 10: 10.0.17763.9245 OR 10.0.19044.7725 OR 10.0.19045.7725
   • Windows 11: 10.0.22631.7582 OR 10.0.26100.9445 OR 10.0.26200.9445 OR 10.0.28000.2954
   • Windows Server 2019: 10.0.17763.9245
   • Windows Server 2022: 10.0.20348.5622
   • Windows Server 2025: 10.0.26100.33438

3. Upgrade/patch

   • Use your normal Windows Update or management process to apply the Microsoft security update(s) for CVE-2026-69874.
   • If you use maintenance windows, prioritize machines with higher odds of local access by untrusted parties (e.g., endpoints used by many users, shared workstations, or systems with extensive third-party software).

4. Verification

   • After patching, re-check the device build number to confirm it matches a fixed version listed above.
   • Confirm Windows Update/servicing is healthy so future updates don’t silently fail.

5. Temporary workaround (if patching is delayed)

   • Reduce the chance of a local attacker gaining “authorized” code execution on the host:
     • limit which accounts can install/run software,
     • restrict local admin where possible,
     • keep endpoint software allowlisted where feasible.
   • These steps do not remove the vulnerability, but they reduce the likelihood someone can exploit it.

6. What to monitor

   • Look for signs of local compromise on high-value machines (unusual account activity, new local admin creation, suspicious software installs, or unexpected processes).
   • Because the issue is local privilege escalation, prioritize alerts tied to post-exploitation behavior (privilege changes, persistence mechanisms) rather than purely remote scanning.

CVE-2026-69874 is a Windows ALPC local elevation of privilege (CWE-822) caused by an untrusted pointer dereference. The attacker model is local and “authorized” (not a purely unauthenticated remote bug), consistent with the access constraints implied by the provided CVSS values. Findings indicate it is not in CISA KEV and there is no public exploit code on record; EPSS is described as a low predicted likelihood with a flat trend, but the overall assigned urgency for this CVE remains RED in the tracker. A fix is available via Microsoft’s update guide, with multiple fixed build numbers across Windows 10/11 and Windows Server branches. KEV status here means there’s no official confirmation of mass exploitation via CISA at the time of this summary.