CVE-2021-21876Public exploitNetwork attack vector

Root command execution via unvalidated TFTP host

Published Dec 22, 2021 · Updated Aug 3, 2024

OS command injection in Lantronix PremierWave 2050 8.9.0.0R4 allows remote authenticated users to execute commands via TFTP PUT. The Web Manager FsTFtp handler inserts the unvalidated host parameter into a shell command passed to exec_system_cmd_ex. A user with writable filesystem permission can send the crafted HTTP request, and the injected command runs with root privileges.

CVSS severity9.1
Critical
EPSS probability2.69%
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 Lantronix PremierWave 2050 8.9.0.0R4 allows remote authenticated users to execute commands via TFTP PUT. The Web Manager FsTFtp handler inserts the unvalidated host parameter into a shell command passed to exec_system_cmd_ex. A user with writable filesystem permission can send the crafted HTTP request, and the injected command runs with root privileges.

The record

CVE
CVE-2021-21876
Published
Dec 22, 2021
Updated
Aug 3, 2024
Vendor
Lantronix
Product
PremierWave 2050
Classifications
CWE-78, T1068, T1059.004
Attack vector
network
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=Lantronix PremierWave 2050 8.9.0.0R4 (in QEMU)

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Lantronix · PremierWave 2050version=Lantronix PremierWave 2050 8.9.0.0R4 (in QEMU)

Published CVSS scores

6.5NIST NVDAV:N/AC:L/Au:S/C:P/I:P/A:P
9.1Cisco TalosCVSS:3.0/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H
9.1NIST NVDCVSS:3.1/AV:N/AC:L/PR:H/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 exploitPublished

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in an OS Command ('OS Command Injection')
T1068Exploitation for Privilege Escalation
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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