CVE-2021-31169Public exploit

SYSTEM elevation via object-directory symbolic-link redirection

Published May 11, 2021 · Updated Aug 3, 2024

Improper privilege management in Windows Container Manager Service allows local users on affected Windows builds to gain SYSTEM privileges. The service creates an AppContainer object directory as SYSTEM without impersonating the caller, so a user-writable symbolic link can redirect creation into \GLOBAL??\KnownDlls. A low-privileged local account can then place a user-controlled section in KnownDlls and load code as SYSTEM.

CVSS severity7.8
High
EPSS probability0.98%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper privilege management in Windows Container Manager Service allows local users on affected Windows builds to gain SYSTEM privileges. The service creates an AppContainer object directory as SYSTEM without impersonating the caller, so a user-writable symbolic link can redirect creation into \GLOBAL??\KnownDlls. A low-privileged local account can then place a user-controlled section in KnownDlls and load code as SYSTEM.

The record

CVE
CVE-2021-31169
Published
May 11, 2021
Updated
Aug 3, 2024
Vendor
Microsoft
Product
Windows Server, version 2004
Classifications
CWE-269, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. May 11, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 3, 2024Record 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=10.0.0 <10.0.19041.982

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Microsoft · Windows Server, version 2004version=10.0.0 <10.0.19041.982
Microsoft · Windows 10 Version 20H2version=10.0.0 <10.0.19042.982
Microsoft · Windows Server version 20H2version=10.0.0 <10.0.19042.982
Microsoft · Windows 10 Version 2004version=10.0.0 <10.0.19041.982

Published CVSS scores

7.8Microsoft CorporationCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
4.6NIST NVDAV:L/AC:L/Au:N/C:P/I:P/A:P

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 exploitPublished

Weakness, pattern, technique

CWE-269Improper Privilege Management
T1068Exploitation for Privilege Escalation

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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