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Microsoft Windows' Heap-Based Buffer Overflow Allows Local Attackers to Escalate Privileges by Corrupting Heap Memory; CISA's September 22nd KEV Deadline Has Passed

Last refreshed2026-09-27

Status: KEV  |  Advisory ID: CVE-2026-85880

Key Details

CVECVE-2026-85880
Vulnerability NameMicrosoft Windows Heap-Based Buffer Overflow Vulnerability
CVSS Score / Version7.8 (High) / CVSS v3.1
Updated2026-09-20
CVSS VectorCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CVSS Proseattack vector is local; attack complexity is low; privileges required is low; user interaction is none; scope is unchanged; confidentiality impact is high; integrity impact is high; availability impact is high.
Affected productssee table below
Exploitation statusListed in CISA's Known Exploited Vulnerabilities (KEV) catalog, indicating confirmed active exploitation.
Classified asCWE-122 (Heap-based Buffer Overflow)
KEV listingAdded to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2026-09-08.
Exploitation prediction (EPSS)3.62% probability of exploitation in the next 30 days (89% percentile) -- FIRST.org's EPSS model.
Federal remediation deadline2026-09-22 (CISA KEV, Binding Operational Directive).

Affected Products, Subsystems & Sectors

VendorProductAffected VersionsPatch Status
MicrosoftWindows
MicrosoftWindows 10 (version 1607)
MicrosoftWindows 10 (version 1809)
MicrosoftWindows 10 (version 21H2)
MicrosoftWindows 10 (version 22H2)
MicrosoftWindows Server 2012
MicrosoftWindows Server 2016
MicrosoftWindows Server 2019
MicrosoftWindows Server 2022
SubsystemsCore Infrastructure, EWS Workstation Delivery/Virtualization
SectorsAll Sectors

What to Know

Microsoft Windows Advanced Local Procedure Call contains a heap-based buffer overflow vulnerability that allows an attacker to elevate privileges locally.

What to Do

Monitor Microsoft's web page for any future patch releases. See vendor advisory link below.

References

SourceReference
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2026-85880
CVEhttps://www.cve.org/CVERecord?id=CVE-2026-85880
Vendor advisoryhttps://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-85880

KEV Required Action

FieldValue
KEV Linkhttps://www.cisa.gov/known-exploited-vulnerabilities-catalog
Date Added to KEV2026-09-08
Required Action Due Date2026-09-22
Required ActionApply 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.

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