Security Advisory Desk
mediumQCS priority 82/100Cisco

Cisco Industrial Ethernet 1000 Series Switches Denial of Service Vulnerability

Cisco found a weakness in their Industrial Ethernet 1000 Series Switches that lets someone from outside overload the system's management features, like the web interface or remote command access, making them stop working. This won’t affect the actual data passing through the switch, but it does block access to control and monitor the device. Cisco has fixed this by releasing updated software and advises users to upgrade. There’s no temporary fix or workaround available.

Published 19/8/2026, 4:00:00 pmVerified 19/8/2026, 7:21:55 pmRevision 1
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In plain language

What this advisory means

Cisco found a weakness in their Industrial Ethernet 1000 Series Switches that lets someone from outside overload the system's management features, like the web interface or remote command access, making them stop working. This won’t affect the actual data passing through the switch, but it does block access to control and monitor the device. Cisco has fixed this by releasing updated software and advises users to upgrade. There’s no temporary fix or workaround available.

Technical explanation

How the issue affects the environment

The Cisco Industrial Ethernet 1000 Series Switches have a vulnerability in how they process management plane packets. The devices do not adequately protect against flooding attacks targeting the management plane. An unauthenticated attacker can exploit this by sending a high volume of ICMP, SSH, or HTTP traffic specifically aimed at management interfaces. This overload causes an increase in CPU usage, leading to a denial of service condition where the device manager web GUI, SSH, and API become unresponsive. Importantly, traffic passing through the switch (data plane traffic) remains unaffected. Cisco addressed this by releasing fixed software versions starting from release 1.9.6, as earlier versions are vulnerable.

Operational impact

Why teams should care

This vulnerability can disrupt network management by making the switch's administration interfaces unavailable, potentially delaying troubleshooting and responses to network issues. Since attackers do not affect data traffic, normal network operations continue, but the inability to access management interfaces poses risks to network security and operational control. Organizations relying on these switches for critical infrastructure management should upgrade promptly to avoid denial of service affecting device administration.

Immediate action

Cisco strongly recommends upgrading Cisco IE 1000 Series Switches to software release 1.9.6 or later to fully remediate this vulnerability and prevent denial of service attacks against the management plane. Customers should obtain the fixed releases from Cisco and apply them according to their support agreements and device configurations.

Affected and fixed releases

Affected versionsEarlier than 1.9
Fixed versions1.9.6

Temporary risk reduction

There are no workarounds or temporary mitigations available for this vulnerability. The only effective remediation is to upgrade to fixed software versions released by Cisco.

Evidence and validation checklist

  • Cisco PSIRT advisory published on August 19, 2026
  • Describes vulnerability in management plane packet handling causing denial of service
  • Exploit involves flooding with ICMP, SSH, or HTTP traffic to increase CPU utilization
  • Management interfaces (web GUI, SSH, API) become inaccessible; data traffic unaffected
  • No workarounds exist; fixed software released starting with version 1.9.6
  • CVE assigned: CVE-2026-20177
  • Cisco indicates vulnerability affects all Cisco IE 1000 Series Switches prior to 1.9

Authoritative reference

Cisco PSIRT Advisories

QCS detected and normalized this record from the official source. Vendor guidance remains authoritative.

Open source