CVE-2020-3120

Device reload via unchecked CDP memory allocation

Published Feb 5, 2020 · Updated Nov 15, 2024

Denial of service in Cisco Discovery Protocol in Cisco IOS XR Software allows attackers to reload affected devices via crafted packets. The message-processing path omits a check and allocates large memory blocks from crafted CDP data until the CDP process crashes and the router reloads. Exploitation requires CDP enabled globally and on an interface plus Layer 2 access to the same broadcast domain; IOS XR disables CDP by default.

CVSS severity7.4
High
EPSS probability1.64%
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 Discovery Protocol in Cisco IOS XR Software allows attackers to reload affected devices via crafted packets. The message-processing path omits a check and allocates large memory blocks from crafted CDP data until the CDP process crashes and the router reloads. Exploitation requires CDP enabled globally and on an interface plus Layer 2 access to the same broadcast domain; IOS XR disables CDP by default.

The record

CVE
CVE-2020-3120
Published
Feb 5, 2020
Updated
Nov 15, 2024
Vendor
ClamAV
Product
Cisco IOS XR Software
Classifications
CWE-190, T1499.002
Attack vector
adjacent
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 5, 2020CVE publishedPublication date reported by the CVE source.
  2. Nov 15, 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=unspecified <2.3.1.173

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOS XR Softwareversion=unspecified <2.3.1.173

Published CVSS scores

7.4Cisco Systems, Inc.CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H/E:X/RL:X/RC:X
6.5NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.1NVDAV:A/AC:L/Au:N/C:N/I:N/A:C

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

Weakness, pattern, technique

CWE-190Integer Overflow or Wraparound
T1499.002Service 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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