CVE-2021-21911Public exploit

NT SYSTEM escalation via replaceable service executable

Published Dec 22, 2021 · Updated Aug 3, 2024

Incorrect default permissions in Advantech R-SeeNet 2.4.16 and earlier allow local users to gain NT SYSTEM privileges on Windows. The default installation grants Authenticated Users change access to C:\R-SeeNet\R_SeeNet.exe, which the SnmpMonSvs service executes as NT SYSTEM. A low-privileged local user must replace that executable and cause the service to restart, enabling arbitrary code execution with system authority.

CVSS severity8.8
High
EPSS probability0.31%
Next 30 days · Sep 17, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect default permissions in Advantech R-SeeNet 2.4.16 and earlier allow local users to gain NT SYSTEM privileges on Windows. The default installation grants Authenticated Users change access to C:\R-SeeNet\R_SeeNet.exe, which the SnmpMonSvs service executes as NT SYSTEM. A low-privileged local user must replace that executable and cause the service to restart, enabling arbitrary code execution with system authority.

The record

CVE
CVE-2021-21911
Published
Dec 22, 2021
Updated
Aug 3, 2024
Vendor
Advantech
Product
R-SeeNet
Classifications
CWE-276, CWE-269, T1574.010
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Dec 22, 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=Advantech R-SeeNet Advantech R-SeeNet 2.4.15 (30.07.2021)

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

Advantech · R-SeeNetversion=Advantech R-SeeNet Advantech R-SeeNet 2.4.15 (30.07.2021)

Published CVSS scores

7.8NIST NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
8.8Cisco TalosCVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
7.2NIST NVDAV:L/AC:L/Au:N/C:C/I:C/A:C

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 11, 2026Sep 17, 2026
Latest reporting daySep 17, 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
CWE-269Improper Privilege Management
T1574.010Hijack Execution Flow: Services 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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