CVE-2026-72971

Authenticated file tampering via link following

Published Aug 11, 2026 · Updated Aug 25, 2026

Link following in unionfs.sys in Windows 11 version 26H1 before 10.0.28000.2704 allows local users to tamper with files. Microsoft has disclosed only that the driver resolves a link before completing file access, so an attacker can redirect the operation to an unintended target path. Exploitation requires local code execution in an authorized context, and the published record bounds the impact to integrity-only tampering rather than code execution, disclosure, or service interruption.

CVSS severity5.5
Medium
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Link following in unionfs.sys in Windows 11 version 26H1 before 10.0.28000.2704 allows local users to tamper with files. Microsoft has disclosed only that the driver resolves a link before completing file access, so an attacker can redirect the operation to an unintended target path. Exploitation requires local code execution in an authorized context, and the published record bounds the impact to integrity-only tampering rather than code execution, disclosure, or service interruption.

The record

CVE
CVE-2026-72971
Published
Aug 11, 2026
Updated
Aug 25, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-59
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 11, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

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

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 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-59Improper Link Resolution Before File Access ('Link Following')

Public exploit references

No public exploit references are available in this record.

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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