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Secure Boot Bypass Vulnerability in CISCO

Indian – Computer Emergency Response Team (https://www.cert-in.org.in)

Severity Rating: HIGH

Systems Affected

Catalyst 9200 Series Switches, including 9200CX and 9200L switches

Catalyst ESS9300 Embedded Series Switches

Catalyst IE9310 and IE9320 Rugged Series Switches

IE3500 and IE3505 Rugged Series Switches

Overview

A vulnerability has been reported in the bootloader of Cisco IOS XE Software for Cisco Catalyst 9200 Series Switches, Cisco Catalyst ESS9300 Embedded Series Switches, Cisco Catalyst IE9310 and IE9320 Rugged Series Switches, and Cisco IE3500 and IE3505 Rugged Series Switches could allow an authenticated, local attacker with level-15 privileges or an unauthenticated attacker with physical access to an affected device to execute arbitrary code at boot time and break the chain of trust.

Target Audience: 

All IT administrators and individuals responsible for maintaining and updating in Software.

Risk Assessment:

High risk of data manipulation and service disruption.

Impact Assessment:

Potential impact on confidentiality, integrity, and availability of the system.

Description

This vulnerability exists due to insufficient validation of software at boot time. An attacker could exploit this vulnerability by manipulating the loaded binaries on an affected device to bypass some of the integrity checks that are performed during the boot process.

Successful exploitation of this vulnerability could allow the attacker to execute code that bypasses the requirement to run Cisco-signed images.

Solution

Apply appropriate updates as mentioned in Cisco Advisory

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-xe-secureboot-bypass-B6uYxYSZ

Vendor Information

CISCO

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-xe-secureboot-bypass-B6uYxYSZ

References

CISCO

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-xe-secureboot-bypass-B6uYxYSZ

CVE Name

CVE-2026-20104

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Thanks and Regards,

CERT-In

Incident Response Help Desk

e-mail: incident@cert-in.org.in

Phone: +91-11-22902657

Toll Free Number: 1800-11-4949

Toll Free Fax : 1800-11-6969

Web: http://www.cert-in.org.in

PGP Fingerprint: A768 083E 4475 5725 B81A A379 2156 C0C0 B620 D0B4

PGP Key information:

https://www.cert-in.org.in/s2cMainServlet?pageid=CONTACTUS

Postal address:

Indian Computer Emergency Response Team (CERT-In)

Ministry of Electronics and Information Technology

Government of India

Electronics Niketan

6, C.G.O. Complex

New Delhi-110 003

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