CVE-2021-1441

Boot-time unsigned code execution via diagnostic script

Published Mar 24, 2021 · Updated Nov 8, 2024

Cisco IOS XE Software on affected 1100 Series and ESR6300 routers allows authenticated local attackers to execute unsigned code at boot. Hardware initialization passes unvalidated parameters to a boot-time diagnostic script, allowing a level-15 administrator who tampers with a stored executable to bypass secure-boot image verification. The consequence is arbitrary code execution with confidentiality, integrity, and availability impact on the router; Cisco reports no public exploitation.

CVSS severity6.7
Medium
EPSS probability0.31%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Cisco IOS XE Software on affected 1100 Series and ESR6300 routers allows authenticated local attackers to execute unsigned code at boot. Hardware initialization passes unvalidated parameters to a boot-time diagnostic script, allowing a level-15 administrator who tampers with a stored executable to bypass secure-boot image verification. The consequence is arbitrary code execution with confidentiality, integrity, and availability impact on the router; Cisco reports no public exploitation.

The record

CVE
CVE-2021-1441
Published
Mar 24, 2021
Updated
Nov 8, 2024
Vendor
ClamAV
Product
Cisco IOS XE Software
Classifications
CWE-78, T1059
Attack vector
local
Privileges
admin

Timeline

How it unfolded

  1. Mar 24, 2021CVE publishedPublication date reported by the CVE source.
  2. Nov 8, 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 vectorlocal
Required privilegesadmin

What is affected?

ClamAV · Cisco IOS XE Softwareversion=n/a

Published CVSS scores

6.7Cisco Systems, Inc.CVSS:3.1/AV:L/AC:L/PR:H/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)
Vectorlocal
Privilegesadmin
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-78Improper Neutralization of Special Elements used in a Command ('Command Injection')
T1059Command and Scripting Interpreter

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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