CVE-2021-28271Public exploit

Local privilege escalation via writable server executable

Published Apr 27, 2021 · Updated Aug 3, 2024

Privilege escalation in Soyal Technologies SOYAL 701Server 9.0.1 allows local users to replace McuServer.exe with arbitrary code. The McuServer.exe access-control list grants Full control to Everyone and Authenticated Users, permitting the installed binary to be overwritten. A standard authenticated Windows account can plant code that runs when the replaced server executable is launched.

CVSS severity8.8
High
EPSS probability1.87%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Privilege escalation in Soyal Technologies SOYAL 701Server 9.0.1 allows local users to replace McuServer.exe with arbitrary code. The McuServer.exe access-control list grants Full control to Everyone and Authenticated Users, permitting the installed binary to be overwritten. A standard authenticated Windows account can plant code that runs when the replaced server executable is launched.

The record

CVE
CVE-2021-28271
Published
Apr 27, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-276, T1574.010
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 27, 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?

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

8.8NIST NVDCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.5NIST NVDAV:N/AC:L/Au:S/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.

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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-276Incorrect Default Permissions
T1574.010Services File Permissions Weakness

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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