CVE-2021-20138Public exploit

Root command execution via unsanitized POST parameters

Published Dec 9, 2021 · Updated Aug 3, 2024

OS command injection in Gryphon Tower firmware 04.0004.12 and earlier allows remote attackers on the same network to execute commands as root. The config_repeater() function in /usr/lib/lua/luci/controller/admin/index.lua concatenates POST parameters into a shell string passed to os.execute without sanitization. Access to the router's local network and its /cgi-bin/luci/rc endpoint is sufficient; injected Bash substitutions run with root privileges.

CVSS severity8.8
High
EPSS probability3.70%
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 Gryphon Tower firmware 04.0004.12 and earlier allows remote attackers on the same network to execute commands as root. The config_repeater() function in /usr/lib/lua/luci/controller/admin/index.lua concatenates POST parameters into a shell string passed to os.execute without sanitization. Access to the router's local network and its /cgi-bin/luci/rc endpoint is sufficient; injected Bash substitutions run with root privileges.

The record

CVE
CVE-2021-20138
Published
Dec 9, 2021
Updated
Aug 3, 2024
Vendor
Gryphon Online Safety, Inc.
Product
Gryphon Tower
Classifications
CWE-78, T1059.004
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Dec 9, 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=<= 04.0004.12 (Current)

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Gryphon Online Safety, Inc. · Gryphon Towerversion=<= 04.0004.12 (Current)

Published CVSS scores

8.8NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.3NIST NVDAV:A/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 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectoradjacent
Privilegesunauthenticated
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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