CVE-2026-20084: A vulnerability in the DHCP snooping feature of Cisco IOS XE Software could allow an unauthenticated, remote a

This month

HIGH 8.6REMOTEMITIGATE

CVE-2026-20084 is a high-severity flaw (CVSS 8.6) affecting ios xe. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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 exploi

Why this priority

High severity
Remotely exploitable, no login, no user action

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	8.6 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	0.4% (top 70%)
CISA exploited list	No
Weakness	CWE-400
Published	2026-03-25
Last modified	2026-09-28

Publisher (CNA): Cisco Systems, Inc. · Vendor: cisco

Last updated 2026-09-28 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-03-25 16:16 UTCPublished CVE record published
2026-09-28 15:18 UTCUpdated Record last modified

cisco ios xe MITIGATE

Affected: 16.6.1 · 16.6.2 · 16.6.3 · 16.6.4 · 16.6.4a · 16.6.5 · 16.6.6 · 16.6.7

Fixed in: no fixed release known

Safe to downgrade to: a release before 16.6.1

Check your OS release

cat /etc/os-release; uname -r

Debian / Ubuntu

sudo apt update && sudo apt full-upgrade

RHEL / Amazon Linux / Fedora

sudo dnf upgrade --refresh

Windows

Install the latest cumulative update from Windows Update

If no patch exists yet

OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.

Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2026-20084?

ios xe: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-20084 being exploited?

CVE-2026-20084 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-20084 affect?

CVE-2026-20084 affects ios xe. Severity is high (CVSS 8.6). 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 vulnerabi

How urgent is CVE-2026-20084?

Priority 42/100. High severity; Remotely exploitable, no login, no user action

Software pages

iOS vulnerabilities · Cisco IOS XE vulnerabilities · Cisco vulnerabilities

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References

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