CVE-2021-20137

Name: CVE-2021-20137
Creator: NVD / NIST
Published: 2021-12-09T16:15:07.753+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 6.1/10EPSS 2.56%

Last modified Jun 17, 2026

CVE-2021-20137 is a medium-severity vulnerability rated 6.1/10 on the CVSS scale. A reflected cross-site scripting vulnerability exists in the url parameter of the /cgi-bin/luci/site_access/ page on the Gryphon Tower router's web interface. An attacker could exploit this issue by tricking a user into following a specially crafted link, granting the attacker javascript execution in the context of the victim's browser.. EPSS estimates a 2.56% chance of exploitation in the next 30 days.

Description

A reflected cross-site scripting vulnerability exists in the url parameter of the /cgi-bin/luci/site_access/ page on the Gryphon Tower router's web interface. An attacker could exploit this issue by tricking a user into following a specially crafted link, granting the attacker javascript execution in the context of the victim's browser.

Metrics

CVSS 3.1

6.1/10

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

EPSS Probability

2.56%

83.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-79

Affected Software

Vendor	Product	Versions
Gryphonconnect	Gryphon Tower Firmware	<= 04.0004.12

References

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

Timeline

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

Frequently Asked Questions

What is CVE-2021-20137?

How severe is CVE-2021-20137?

CVE-2021-20137 has a CVSS score of 6.1/10 (MEDIUM severity). The EPSS model estimates a 2.56% probability of exploitation in the next 30 days.

How do I fix CVE-2021-20137?

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-2021-20137?

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

Scan your code now

Source: NVD / NIST