CVE-2021-26273Public exploit

SYSTEM privilege escalation via writable installer executable

Published Jul 7, 2021 · Updated Aug 3, 2024

Incorrect access control in NinjaRMM Agent 5.0.909 allows local users to execute arbitrary code as NT AUTHORITY\SYSTEM during MSI repair. The EXEMSI-generated installer uses a user-writable %TEMP%\MW- directory, then executes the expected EXE as SYSTEM without impersonating the invoking user. A non-administrative local user must start a repair, win the file-placement race, and lock the replacement executable before MSIExec launches it.

CVSS severity7.8
High
EPSS probability0.38%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Incorrect access control in NinjaRMM Agent 5.0.909 allows local users to execute arbitrary code as NT AUTHORITY\SYSTEM during MSI repair. The EXEMSI-generated installer uses a user-writable %TEMP%\MW- directory, then executes the expected EXE as SYSTEM without impersonating the invoking user. A non-administrative local user must start a repair, win the file-placement race, and lock the replacement executable before MSIExec launches it.

The record

CVE
CVE-2021-26273
Published
Jul 7, 2021
Updated
Aug 3, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-863, T1068
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Jul 7, 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

7.8NIST NVDCVSS: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-863Incorrect Authorization
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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