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Vulnerabilities

Vulnerability · 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 VL…

Published Mar 25, 2026 · catalog updated Sep 28, 2026 · ios xe

Check if you run it

No confirmed exploitation is on record for CVE-2026-20084. EPSS is 0.35%. Act only if a listed version of ios xe is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
High8.6
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.35%
Remediation
Advisory link
Affected products
cpe cisco/ios xe

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe cisco/ios xe16.6.1
  • cpe cisco/ios xe16.6.2
  • cpe cisco/ios xe16.6.3
  • cpe cisco/ios xe16.6.4
  • cpe cisco/ios xe16.6.4a
  • cpe cisco/ios xe16.6.5
  • cpe cisco/ios xe16.6.6
  • cpe cisco/ios xe16.6.7

How to fix CVE-2026-20084

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-20084. EPSS is 0.35%. Act only if a listed version of ios xe is installed.

Which versions are affected?

Compare what you have installed with cisco/ios xe 16.6.1; cisco/ios xe 16.6.2; cisco/ios xe 16.6.3; cisco/ios xe 16.6.4. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-400: Uncontrolled Resource Consumption. EPSS 0.35%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

Cisco security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Mar 25, 2026 · NIST NVD

    Detected

    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 pack

  2. Sep 28, 2026 · NIST NVD

    Updated

    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 pack

Sources

  • CVE.orgVulnerability recordCVE-2026-20084

    Official CVE identifier

    cve.org
  • FIRST EPSSExploitation probabilityCVE-2026-20084

    30-day exploitation probability 0.4%

    first.org
  • NIST NVDVulnerability recordCVE-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 BOOT

    nvd.nist.gov

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.