CVE-2022-20756: A vulnerability in the RADIUS feature of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to cause the affected sy...

Description

A vulnerability in the RADIUS feature of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to cause the affected system to stop processing RADIUS packets. This vulnerability is due to improper handling of certain RADIUS requests. An attacker could exploit this vulnerability by attempting to authenticate to a network or a service where the access server is using Cisco ISE as the RADIUS server. A successful exploit could allow the attacker to cause Cisco ISE to stop processing RADIUS requests, causing authentication/authorization timeouts, which would then result in legitimate requests being denied access. Note: To recover the ability to process RADIUS packets, a manual restart of the affected Policy Service Node (PSN) is required. See the Details section for more information.

Metrics

CVSS 3.1

7.5/10

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

EPSS Probability

1.43%

69.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-399

Affected Software

Vendor	Product	Versions	Update
Cisco	Identity Services Engine	2.2.0	Patch17
Cisco	Identity Services Engine	2.4.0	Patch12
Cisco	Identity Services Engine	2.6.0	Patch10
Cisco	Identity Services Engine	2.7.0	Patch2
Cisco	Identity Services Engine	2.7.0.356	Patch1
Cisco	Identity Services Engine	3.0.0	—
Cisco	Identity Services Engine	3.1	—

References

Timeline

Published: Apr 6, 2022
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2022-20756?

A vulnerability in the RADIUS feature of Cisco Identity Services Engine (ISE) could allow an unauthenticated, remote attacker to cause the affected system to stop processing RADIUS packets. This vulnerability is due to improper handling of certain RADIUS requests. An attacker could exploit this vulnerability by attempting to authenticate to a network or a service where the access server is using Cisco ISE as the RADIUS server. A successful exploit could allow the attacker to cause Cisco ISE to stop processing RADIUS requests, causing authentication/authorization timeouts, which would then result in legitimate requests being denied access. Note: To recover the ability to process RADIUS packets, a manual restart of the affected Policy Service Node (PSN) is required. See the Details section for more information.

How severe is CVE-2022-20756?

CVE-2022-20756 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.43% probability of exploitation in the next 30 days.

How do I fix CVE-2022-20756?

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.