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CVE-2026-85880

Microsoft — Microsoft Windows Heap-Based Buffer Overflow Vulnerability

Microsoft · CWE-122 | CWE-908 · in CISA KEV since 2026-09-08

CISA federal deadline · Overdue by 31 daysCISA KEVActively Exploited
75

EVRS 75 of 100 Urgent

Patch This Cycle

Raised to the floor for a confirmed exploited vulnerability.

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Why it scores 75

Evidence available: 6 of 8 signals

Listed in the CISA KEV catalog, and an EPSS probability of 0.036.

  • CISA KEVApplied
  • RansomwareDid not apply
  • Vendor exploitationDid not apply
  • EPSSApplied
  • Microsoft Exploitability IndexNo data
  • Pre-patch disclosureNo data
  • KEV recencyApplied
  • CVSSApplied

The band answers “how soon”, not “how bad”. No data for: Microsoft Exploitability Index, Pre-patch disclosure. Why some signals show no data

Fix

Patch or fixed version identified

CISA required action

Fixed in

windows 10 1607: update to 10.0.14393.9512 or later | windows 10 1809: update to 10.0.17763.9245 or later | windows 10 21h2: update to 10.0.19044.7725 or later | windows 10 22h2: update to 10.0.19045.7725 or later | windows server 2016: update to 10.0.14393.9512 or later | windows server 2019: update to 10.0.17763.9245 or later

Affected versions

  • windows 10 1607< 10.0.14393.9512
  • windows 10 1809< 10.0.17763.9245
  • windows 10 21h2< 10.0.19044.7725
  • windows 10 22h2< 10.0.19045.7725
  • windows server 2012r2
  • windows server 2016< 10.0.14393.9512
  • windows server 2019< 10.0.17763.9245
  • windows server 2022< 10.0.20348.5622

Remediation

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.

Fixed versions from NVD.

Evidence

Each value with its source
MeasureValueSource
CVSS base scoreHow severe the flaw is in itself. It does not say how likely an attack is. 7.8 NVD
FIRST EPSSFIRST's estimate of the chance this is exploited in the next 30 days, and how that ranks against all CVEs. 0.036 (89.5th pctl) FIRST EPSS
Actively exploitedWhether a source of record has confirmed attacks using it in the wild. Confirmed CISA KEV
Ransomware campaign useWhether CISA has seen ransomware operators use it. Unknown or none CISA KEV
CISA remediation deadlineThe date US federal agencies must have fixed or mitigated it. 2026-09-22 · CISA federal deadline · Overdue by 31 days CISA KEV
Public exploit moduleA module existing is not the same as active exploitation. None known Metasploit
EUVD cross-referenceENISA's record: CVSS 7.8 (v3.1), assigned by microsoft. Listed ENISA EUVD

Description

NVD

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

What CISA says to do