CVE-2021-39244Public exploitNetwork attack vector

Authenticated command execution via unfiltered tcpdump parameters

Published Aug 23, 2021 · Updated Aug 4, 2024

OS command injection in Altus Nexto, Nexto Xpress, and Hadron Xtorm firmware allows remote authenticated users to execute arbitrary commands. The getlogs.cgi script URL-decodes tcpdump_iface and tcpdump_count query values, then expands them unquoted into a tcpdump command; injected flags make tcpdump invoke sh on a capture file. Access to the HTTP Basic-authenticated endpoint and network reachability to the device are required, after which commands run on the PLC and their output can be retrieved from capture.pcap.

CVSS severity8.8
High
EPSS probability3.48%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OS command injection in Altus Nexto, Nexto Xpress, and Hadron Xtorm firmware allows remote authenticated users to execute arbitrary commands. The getlogs.cgi script URL-decodes tcpdump_iface and tcpdump_count query values, then expands them unquoted into a tcpdump command; injected flags make tcpdump invoke sh on a capture file. Access to the HTTP Basic-authenticated endpoint and network reachability to the device are required, after which commands run on the PLC and their output can be retrieved from capture.pcap.

The record

CVE
CVE-2021-39244
Published
Aug 23, 2021
Updated
Aug 4, 2024
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-78, T1059.004
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Aug 23, 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?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

8.8INCIBE-CERTCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/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 exploitPublished

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1059.004Unix Shell

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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