CVE-2023-20156Network attack vector

Device denial of service via crafted web request

Published May 18, 2023 · Updated Oct 28, 2024

Heap buffer overflow in the web UI of Cisco Small Business Smart and Managed Switches allows remote attackers to interrupt affected devices. The interface improperly validates a crafted request before processing it, causing a heap buffer overflow; Cisco has not identified the affected handler or field. No authentication or user interaction is required, and the documented consequence for this CVE is device denial of service rather than code execution.

CVSS severity8.6
High
EPSS probability1.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Heap buffer overflow in the web UI of Cisco Small Business Smart and Managed Switches allows remote attackers to interrupt affected devices. The interface improperly validates a crafted request before processing it, causing a heap buffer overflow; Cisco has not identified the affected handler or field. No authentication or user interaction is required, and the documented consequence for this CVE is device denial of service rather than code execution.

The record

CVE
CVE-2023-20156
Published
May 18, 2023
Updated
Oct 28, 2024
Vendor
ClamAV
Product
Cisco Business 350 Series Managed Switches
Classifications
CWE-120, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 18, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 28, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=0 <3.3.0.16

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco Business 350 Series Managed Switchesversion=0 <3.3.0.16
ClamAV · Cisco Business 250 Series Smart Switchesversion=0 <3.3.0.16
ClamAV · Cisco Small Business 300 Series Managed Switchesversion=0 <*
ClamAV · Cisco Small Business Smart and Managed Switchesversion=n/a
ClamAV · Cisco 550X Series Stackable Managed Switchesversion=0 <2.5.9.16
ClamAV · Cisco 250 Series Smart Switchesversion=0 <2.5.9.16
ClamAV · Cisco Small Business 200 Series Smart Switchesversion=0 <*
ClamAV · Cisco 350X Series Stackable Managed Switchesversion=0 <2.5.9.16
ClamAV · Cisco 350 Series Managed Switchesversion=0 <2.5.9.16
ClamAV · Cisco Small Business 500 Series Stackable Managed Switchesversion=0 <*

Published CVSS scores

8.6Cisco Systems, Inc.CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

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.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
T1499Endpoint Denial of Service

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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