CVE-2021-35223Network attack vector

Authenticated command execution via unsanitized SITE EXEC parameters

Published Aug 31, 2021 · Updated Aug 4, 2024

Command injection in SolarWinds Serv-U 15.2.3 and earlier allows remote authenticated users to execute code through FTP SITE EXEC. SITE EXEC passes improperly sanitized user-supplied parameters to ShellExecuteExW, enabling command-line injection. The user must have SITE EXEC access and execute permission on the target folder; commands run in the file-server process context.

CVSS severity8.5
High
EPSS probability2.94%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Command injection in SolarWinds Serv-U 15.2.3 and earlier allows remote authenticated users to execute code through FTP SITE EXEC. SITE EXEC passes improperly sanitized user-supplied parameters to ShellExecuteExW, enabling command-line injection. The user must have SITE EXEC access and execute permission on the target folder; commands run in the file-server process context.

The record

CVE
CVE-2021-35223
Published
Aug 31, 2021
Updated
Aug 4, 2024
Vendor
SolarWinds
Product
Serv-U
Classifications
T1059
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 31, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 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=15.2.3 and previous versions <=15.2.4

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

SolarWinds · Serv-Uversion=15.2.3 and previous versions <=15.2.4

Published CVSS scores

8.5SolarWindsCVSS:3.0/AV:N/AC:H/PR:L/UI:N/S:C/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)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1059Command and Scripting Interpreter

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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