CVE-2026-20124: A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS XE Software could allo

Routine

HIGH 7.7MITIGATE

CVE-2026-20124 is a high-severity flaw (CVSS 7.7) 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 Simple Network Management Protocol (SNMP) subsystem of Cisco IOS XE Software could allow an authenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. This vulnerability is due to improper error handling when parsing SNMP requests. This vulnerability affects all versions of SNMP — Versions 1, 2c, and 3. An attacker could exploit this vulnerability by send

Why this priority

High severity

A fixed release or distro patch exists.

Risk facts

CVSS score	7.7 (High)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.5% (top 58%)
CISA exploited list	No
Weakness	CWE-772
Published	2026-08-05
Last modified	2026-10-23

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

Last updated 2026-10-23 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-08-05 17:16 UTCPublished CVE record published
2026-10-23 21:10 UTCUpdated Record last modified

cisco ios xe MITIGATE

Affected: 3.13.9s · 3.13.10s · 3.16.6bs · 3.16.7as · 3.16.7bs · 3.16.7s · 3.16.8s · 3.16.9s

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.13.9s

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.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · sugar-toolkit-gtk3 · FIXED · 0.122-2.fc46 · FEDORA-2026-d11eb2faf0 · source

sudo dnf upgrade --advisory=FEDORA-2026-d11eb2faf0

Fedora ELN · ntpd-rs · FIXED · 1.7.2-3.eln159 · FEDORA-2026-57e4a99310 · source

sudo dnf upgrade --advisory=FEDORA-2026-57e4a99310

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-2026-20124?

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

Is CVE-2026-20124 being exploited?

CVE-2026-20124 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-2026-20124 affect?

CVE-2026-20124 affects ios xe. Severity is high (CVSS 7.7). A vulnerability in the Simple Network Management Protocol (SNMP) subsystem of Cisco IOS XE Software could allow an authenticated, remote attacker to cause an affected device to reload, resulting in a denial of service (DoS) condition. Th

How urgent is CVE-2026-20124?

Priority 37/100. High severity

Software pages

iOS vulnerabilities · Cisco IOS XE vulnerabilities · Cisco vulnerabilities

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References

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