CVE-2023-20081Network attack vector

Device reload via malformed DHCPv6 message processing

Published Mar 23, 2023 · Updated Oct 25, 2024

Denial of service in the DHCPv6 client of Cisco IOS allows remote attackers to reload affected devices via crafted DHCPv6 messages. The client insufficiently validates DHCPv6 messages before processing them, allowing malformed server input to trigger a heap-based buffer overflow and device reload. Exploitation requires IPv6 unicast routing and the DHCPv6 client to be enabled, plus control of the DHCPv6 server or a man-in-the-middle position.

CVSS severity6.8
Medium
EPSS probability0.68%
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 the DHCPv6 client of Cisco IOS allows remote attackers to reload affected devices via crafted DHCPv6 messages. The client insufficiently validates DHCPv6 messages before processing them, allowing malformed server input to trigger a heap-based buffer overflow and device reload. Exploitation requires IPv6 unicast routing and the DHCPv6 client to be enabled, plus control of the DHCPv6 server or a man-in-the-middle position.

The record

CVE
CVE-2023-20081
Published
Mar 23, 2023
Updated
Oct 25, 2024
Vendor
ClamAV
Product
Cisco IOS
Classifications
CWE-122, T1499
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Mar 23, 2023CVE publishedPublication date reported by the CVE source.
  2. Oct 25, 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?

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  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOSversion=n/a

Published CVSS scores

6.8CiscoCVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X

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-122Heap-based 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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