CVE-2023-20072: A vulnerability in the fragmentation handling code of tunnel protocol packets in Cisco IOS XE Software could allow an unauthenticated, remote attacker...

Description

A vulnerability in the fragmentation handling code of tunnel protocol packets in Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected system to reload, resulting in a denial of service (DoS) condition. This vulnerability is due to the improper handling of large fragmented tunnel protocol packets. One example of a tunnel protocol is Generic Routing Encapsulation (GRE). An attacker could exploit this vulnerability by sending crafted fragmented packets to an affected system. A successful exploit could allow the attacker to cause the affected system to reload, resulting in a DoS condition. Note: Only traffic directed to the affected system can be used to exploit this vulnerability.

Metrics

CVSS 3.1

8.6/10

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

EPSS Probability

0.98%

57.7th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-20

Affected Software

Vendor	Product	Versions
Cisco	Ios Xe	17.9.1
Cisco	Ios Xe	17.9.1a
Cisco	Ios Xe	17.9.1w

References

Timeline

Published: Mar 23, 2023
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2023-20072?

A vulnerability in the fragmentation handling code of tunnel protocol packets in Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause an affected system to reload, resulting in a denial of service (DoS) condition. This vulnerability is due to the improper handling of large fragmented tunnel protocol packets. One example of a tunnel protocol is Generic Routing Encapsulation (GRE). An attacker could exploit this vulnerability by sending crafted fragmented packets to an affected system. A successful exploit could allow the attacker to cause the affected system to reload, resulting in a DoS condition. Note: Only traffic directed to the affected system can be used to exploit this vulnerability.

How severe is CVE-2023-20072?

CVE-2023-20072 has a CVSS score of 8.6/10 (HIGH severity). The EPSS model estimates a 0.98% probability of exploitation in the next 30 days.

How do I fix CVE-2023-20072?

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.