CVE-2026-42976

Local privilege escalation via unauthenticated RPC function

Published Aug 11, 2026 · Updated Aug 25, 2026

Missing authentication in the Windows RPC API allows local users with low privileges to elevate privileges on affected Windows releases. Microsoft identifies the locus only as a critical function exposed by the Windows RPC API; it has not published the RPC interface, endpoint, or operation that omits authentication. Exploitation requires existing low-privilege local access and grants higher Windows privileges, with confidentiality, integrity, and availability consequences.

CVSS severity7.8
High
EPSS probability0.21%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Missing authentication in the Windows RPC API allows local users with low privileges to elevate privileges on affected Windows releases. Microsoft identifies the locus only as a critical function exposed by the Windows RPC API; it has not published the RPC interface, endpoint, or operation that omits authentication. Exploitation requires existing low-privilege local access and grants higher Windows privileges, with confidentiality, integrity, and availability consequences.

The record

CVE
CVE-2026-42976
Published
Aug 11, 2026
Updated
Aug 25, 2026
Vendor
Microsoft
Product
Windows Server 2019
Classifications
CWE-306, T1068
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

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

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

  1. Affected versionversion=10.0.17763.0 <10.0.17763.9121

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Windows Server 2019version=10.0.17763.0 <10.0.17763.9121
Microsoft · Windows Server 2025 (Server Core installation)version=10.0.26100.0 <10.0.26100.33296
Microsoft · Windows 11, version 25H2version=10.0.26200.0 <10.0.26200.9168
Microsoft · Windows Server 2016 (Server Core installation)version=10.0.14393.0 <10.0.14393.9418
Microsoft · Windows 11, version 24H2version=10.0.26100.0 <10.0.26100.9168
Microsoft · Windows Server 2012 (Server Core installation)version=6.2.9200.0 <6.2.9200.26280
Microsoft · Windows Server 2012version=6.2.9200.0 <6.2.9200.26280
Microsoft · Windows 10 Version 21H2version=10.0.19044.0 <10.0.19044.7663
Microsoft · Windows Server 2016version=10.0.14393.0 <10.0.14393.9418
Microsoft · Windows 10 Version 22H2version=10.0.19045.0 <10.0.19045.7663
Microsoft · Windows Server 2012 R2 (Server Core installation)version=6.3.9600.0 <6.3.9600.23338
Microsoft · Windows Server 2019 (Server Core installation)version=10.0.17763.0 <10.0.17763.9121
Microsoft · Windows 11, version 26H1version=10.0.28000.0 <10.0.28000.2704
Microsoft · Windows 10 Version 1607version=10.0.14393.0 <10.0.14393.9418
Microsoft · Windows Server 2022version=10.0.20348.0 <10.0.20348.5499
Microsoft · Windows Server 2025version=10.0.26100.0 <10.0.26100.33296
Microsoft · Windows 10 Version 1809version=10.0.17763.0 <10.0.17763.9121
Microsoft · Windows Server 2012 R2version=6.3.9600.0 <6.3.9600.23338

Published CVSS scores

7.8Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

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 exploitUnconfirmed

Weakness, pattern, technique

CWE-306Missing Authentication for Critical Function
T1068Exploitation for Privilege Escalation

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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