CVE-2026-20177Network attack vector

Management-service outage via unthrottled packet flooding

Published Aug 19, 2026 · Updated Aug 20, 2026

Denial of service in Cisco IE 1000 Series Switches allows remote attackers to interrupt management access with high-rate traffic. Management-plane packet handling does not throttle high-rate ICMP, SSH, or HTTP traffic, allowing CPU usage to rise until the web GUI, SSH, and API become inaccessible. No authentication or special configuration is required; data forwarding remains unaffected while management access is unavailable.

CVSS severity5.3
Medium
EPSS probability0.39%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in Cisco IE 1000 Series Switches allows remote attackers to interrupt management access with high-rate traffic. Management-plane packet handling does not throttle high-rate ICMP, SSH, or HTTP traffic, allowing CPU usage to rise until the web GUI, SSH, and API become inaccessible. No authentication or special configuration is required; data forwarding remains unaffected while management access is unavailable.

The record

CVE
CVE-2026-20177
Published
Aug 19, 2026
Updated
Aug 20, 2026
Vendor
Unknown vendor
Product
Unknown product
Classifications
CWE-770, T1499.003
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Aug 19, 2026CVE publishedPublication date reported by the CVE source.
  2. Aug 20, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Affected buildAffected product and version details are unavailable.

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Affected products and versions are unavailable in this record.

Published CVSS scores

5.3CiscoCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-770Allocation of Resources Without Limits or Throttling
T1499.003Application Exhaustion Flood

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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