CVE-2026-20084: A vulnerability in the DHCP snooping feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause BOOTP packets to be for...

Description

A vulnerability in the DHCP snooping feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause BOOTP packets to be forwarded between VLANs, resulting in a denial of service (DoS) condition. This vulnerability is due to improper handling of BOOTP packets on Cisco Catalyst 9000 Series Switches. An attacker could exploit this vulnerability by sending BOOTP request packets to an affected device. A successful exploit could allow an attacker to forward BOOTP packets from one VLAN to another, resulting in BOOTP VLAN leakage and potentially leading to high CPU utilization. This makes the device unreachable (either through console or remote management) and unable to forward traffic, resulting in a DoS condition. Note: This vulnerability can be exploited with either unicast or broadcast BOOTP packets. There are workarounds that address 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

0.35%

27.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-400

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

Vendor	Product	Versions
Cisco	Cisco IOS XE Software	16.6.1; 16.6.2; 16.6.3; 16.6.4; 16.6.5; 16.6.4a; 16.6.6; 16.6.7; 16.6.8; 16.6.9; 16.6.10; 16.7.1; 16.8.1; 16.8.1a; 16.8.1s; 16.9.1; 16.9.2; 16.9.1s; 16.9.3; 16.9.4; 16.9.5; 16.9.6; 16.9.7; 16.9.8; 16.10.1; 16.10.1s; 16.10.1e; 16.11.1; 16.11.1b; 16.11.1s; 16.12.1; 16.12.1s; 16.12.1c; 16.12.2; 16.12.3; 16.12.8; 16.12.2s; 16.12.4; 16.12.3s; 16.12.3a; 16.12.4a; 16.12.5; 16.12.6; 16.12.5b; 16.12.6a; 16.12.7; 17.1.1; 17.1.1s; 17.1.1t; 17.1.3; 17.2.1; 17.2.1a; 17.3.1; 17.3.2; 17.3.3; 17.3.2a; 17.3.4; 17.3.5; 17.3.6; 17.3.7; 17.3.8; 17.3.8a; 17.4.1; 17.5.1; 17.6.1; 17.6.2; 17.6.3; 17.6.1y; 17.6.4; 17.6.5; 17.6.6; 17.6.6a; 17.6.5a; 17.6.7; 17.6.8; 17.7.1; 17.10.1; 17.10.1b; 17.8.1; 17.9.1; 17.9.2; 17.9.3; 17.9.4; 17.9.5; 17.9.4a; 17.9.6; 17.9.6a; 17.9.7; 17.9.8; 17.11.1; 17.12.1; 17.12.2; 17.12.3; 17.12.4; 17.12.5; 17.12.1z5; 17.13.1; 17.14.1; 17.15.1; 17.15.2; 17.15.3; 17.15.2b; 17.15.4; 17.15.4d; 17.16.1; 17.17.1; 17.18.1

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-bootp-WuBhNBxA

Timeline

Published: Mar 25, 2026
Last Modified: Jun 17, 2026
Status: Awaiting Analysis

Frequently Asked Questions

What is CVE-2026-20084?

A vulnerability in the DHCP snooping feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause BOOTP packets to be forwarded between VLANs, resulting in a denial of service (DoS) condition. This vulnerability is due to improper handling of BOOTP packets on Cisco Catalyst 9000 Series Switches. An attacker could exploit this vulnerability by sending BOOTP request packets to an affected device. A successful exploit could allow an attacker to forward BOOTP packets from one VLAN to another, resulting in BOOTP VLAN leakage and potentially leading to high CPU utilization. This makes the device unreachable (either through console or remote management) and unable to forward traffic, resulting in a DoS condition. Note: This vulnerability can be exploited with either unicast or broadcast BOOTP packets. There are workarounds that address this vulnerability.

How severe is CVE-2026-20084?

CVE-2026-20084 has a CVSS score of 8.6/10 (HIGH severity). The EPSS model estimates a 0.35% probability of exploitation in the next 30 days.

How do I fix CVE-2026-20084?

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.

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