CVE-2022-20731

Persistent code execution via improper Secure Boot enforcement

Published Apr 15, 2022 · Updated Nov 6, 2024

Improper Secure Boot enforcement in Cisco IOS ROMMON Software allows attackers to execute persistent code at boot by loading unsigned code. The boot loader does not properly enable Secure Boot, so it accepts unsigned code and breaks the device's chain of trust before the operating system starts. Exploitation requires either physical access without authentication or a local level 15 session, and the resulting code persists across boots on affected CDB-8P and CDB-8U switches.

CVSS severity6.8
Medium
EPSS probability0.24%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper Secure Boot enforcement in Cisco IOS ROMMON Software allows attackers to execute persistent code at boot by loading unsigned code. The boot loader does not properly enable Secure Boot, so it accepts unsigned code and breaks the device's chain of trust before the operating system starts. Exploitation requires either physical access without authentication or a local level 15 session, and the resulting code persists across boots on affected CDB-8P and CDB-8U switches.

The record

CVE
CVE-2022-20731
Published
Apr 15, 2022
Updated
Nov 6, 2024
Vendor
ClamAV
Product
Cisco IOS ROMMON Software
Classifications
CWE-665, CWE-1221, T1542.003
Attack vector
physical
Privileges
unauthenticated

Timeline

How it unfolded

  1. Apr 15, 2022CVE publishedPublication date reported by the CVE source.
  2. Nov 6, 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=n/a

What conditions does exploitation require?

Attack vectorphysical
Required privilegesunauthenticated

What is affected?

ClamAV · Cisco IOS ROMMON Softwareversion=n/a

Published CVSS scores

4.6Cisco CNACVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
6.8Cisco Security AdvisoryCVSS:3.1/AV:P/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.

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)
Vectorphysical
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-665Improper Initialization
CWE-1221Incorrect Register Defaults or Module Parameters
T1542.003Bootkit

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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