CVE-2026-2636Public exploit

Local system crash via invalid CLFS read

Published Feb 25, 2026 · Updated Feb 25, 2026

Denial of service in Microsoft Windows before 25H2 allows local users to crash the system by reading from an opened CLFS log file. CLFS!CClfsRequest::ReadLogPagingIo mishandles a ReadFile request on a CreateLogFile handle when both expected IRP flags are clear and calls KeBugCheckEx. Low-privilege local access is sufficient; the result is an immediate operating-system crash without data disclosure or modification.

CVSS severity5.5
Medium
EPSS probability0.41%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Microsoft Windows before 25H2 allows local users to crash the system by reading from an opened CLFS log file. CLFS!CClfsRequest::ReadLogPagingIo mishandles a ReadFile request on a CreateLogFile handle when both expected IRP flags are clear and calls KeBugCheckEx. Low-privilege local access is sufficient; the result is an immediate operating-system crash without data disclosure or modification.

The record

CVE
CVE-2026-2636
Published
Feb 25, 2026
Updated
Feb 25, 2026
Vendor
Microsoft
Product
Windows
Classifications
CWE-159, T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Feb 25, 2026CVE publishedPublication date reported by the CVE source.
  2. Feb 25, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <=1123h2
  2. Affected versionversion=0 <25H2

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Windowsversion=0 <=1123h2; version=0 <25H2

Published CVSS scores

5.5FortraCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-159Improper Handling of Invalid Use of Special Elements
T1499.004Application or System Exploitation

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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