CVE intelligenceCISA KEV

CVE-2026-85880

Microsoft Windows Heap-Based Buffer Overflow Vulnerability

Published Sep 8, 2026Sources checked Oct 28, 2026

7.8HIGHCVSS out of 10

What this means

Actively exploited

CISA lists CVE-2026-85880 in its Known Exploited Vulnerabilities catalog, which means exploitation has been observed. The entry applies to Microsoft Windows.

Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.

Public exploit: Not collected.

Microsoft Security Response Center: Exploitation reported by Microsoft Security Response Center (2026-09-16)
Microsoft exploitation status: Exploited:Yes

What to do next

Remediation and response

Review the linked vendor advisory and apply the mitigation or fixed release for your affected product.

Microsoft Security Response Center guidance

Vendor revision: Sep 16, 2026

Vendor remediation details

Install KB5122876. Install KB5122882. Install KB5122878. Install KB5123099. Install KB5123065. Install KB5123066.

Vendor-listed releases

10.0.17763.9245
10.0.20348.5622
10.0.19044.7725
10.0.19045.7725
10.0.14393.9512
6.2.9200.26349
6.3.9600.23398

CISA KEVListedObserved exploitation

EPSS0.4%Estimated 30-day exploitation probability

Ransomware useNot markedCISA KEV ransomware field

Threat actors1Source-linked actor relationships

Overview

What is CVE-2026-85880?

Heap-based buffer overflow in Windows ALPC allows an authorized attacker to elevate privileges locally.

Source: NVD

Reported activity: Microsoft exploitation status: Exploited:Yes
Microsoft Security Response Center · Published Sep 16, 2026

CISA says:Apply mitigations in accordance with vendor instructions, ensuring compliance with CISA’s BOD 26-04 Prioritizing Security Updates Based on Risk (see URL in Notes) guidance and CISA’s “Forensics Triage Requirements” (see URL in Notes). Follow applicable BOD 26-04 guidance for cloud services or discontinue use of the product if mitigations are unavailable. Stakeholders are responsible for evaluating each asset's internet exposure and ensuring adherence to BOD 26-04 patching guidelines.CISA catalog due date Sep 22, 2026