CVE-2021-20138

Name: CVE-2021-20138
Creator: NVD / NIST
Published: 2021-12-09T16:15:07.803+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

HIGHCVSS 8.8/10EPSS 3.70%

Last modified Jun 17, 2026

CVE-2021-20138 is a high-severity vulnerability rated 8.8/10 on the CVSS scale. An unauthenticated command injection vulnerability exists in multiple parameters in the Gryphon Tower router’s web interface at /cgi-bin/luci/rc. An unauthenticated remote attacker on the same network can execute commands as root on the device by sending a specially crafted malicious packet to the web interface.. EPSS estimates a 3.70% chance of exploitation in the next 30 days.

Description

An unauthenticated command injection vulnerability exists in multiple parameters in the Gryphon Tower router’s web interface at /cgi-bin/luci/rc. An unauthenticated remote attacker on the same network can execute commands as root on the device by sending a specially crafted malicious packet to the web interface.

Metrics

CVSS 3.1

8.8/10

CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability

3.70%

88.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-78

Affected Software

Vendor	Product	Versions
Gryphonconnect	Gryphon Tower Firmware	<= 04.0004.12

References

https://www.tenable.com/security/research/tra-2021-51Exploit, Vendor Advisory
https://www.tenable.com/security/research/tra-2021-51Exploit, Vendor Advisory

Timeline

Published: Dec 9, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-20138?

How severe is CVE-2021-20138?

CVE-2021-20138 has a CVSS score of 8.8/10 (HIGH severity). The EPSS model estimates a 3.70% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20138?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-20138?

Run a free Strix scan to check your systems for this vulnerability.

Scan your code now

Source: NVD / NIST