CVE-2020-3111Public exploit

Root code execution via unchecked PortID TLV length

Published Feb 5, 2020 · Updated Nov 15, 2024

Stack overflow in Cisco IP Phone firmware before 12.7(1) allows remote attackers to execute code as root or reload the device via CDP packets. The cdpRcvParse function in the root-privileged cdpd daemon trusts the PortID TLV length and copies its value into a fixed-size stack buffer without a bounds check. Exploitation requires Cisco Discovery Protocol to be enabled and Layer 2 access to the phone's broadcast domain; success grants root execution or forces a reboot.

CVSS severity8.8
High
EPSS probability3.09%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack overflow in Cisco IP Phone firmware before 12.7(1) allows remote attackers to execute code as root or reload the device via CDP packets. The cdpRcvParse function in the root-privileged cdpd daemon trusts the PortID TLV length and copies its value into a fixed-size stack buffer without a bounds check. Exploitation requires Cisco Discovery Protocol to be enabled and Layer 2 access to the phone's broadcast domain; success grants root execution or forces a reboot.

The record

CVE
CVE-2020-3111
Published
Feb 5, 2020
Updated
Nov 15, 2024
Vendor
Cisco
Product
Cisco IP Phone
Classifications
CWE-20, T1210
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 <12.7(1)

What conditions does exploitation require?

Attack vectoradjacent
Required privilegesunauthenticated

What is affected?

Cisco · Cisco IP Phoneversion=unspecified <12.7(1)

Published CVSS scores

8.3NIST NVDAV:A/AC:L/Au:N/C:C/I:C/A:C
8.8Cisco Systems, Inc.CVSS:3.0/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
8.8NIST NVDCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/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.

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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)
Vectoradjacent
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

CWE-20Improper Input Validation
T1210Exploitation of Remote Services

Public exploit references

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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