CVE-2026-20104

March 26, 2026, 3:13 p.m.

6.1
Medium

Description

A vulnerability 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. This vulnerability is 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. A successful exploit could allow the attacker to execute code that bypasses the requirement to run Cisco-signed images. Cisco has assigned this security advisory a Security Impact Rating (SIR) of High rather than Medium as the score indicates because this vulnerability allows an attacker to bypass a major security feature of a device.

Product(s) Impacted

Vendor Product Versions
Cisco
  • Catalyst 9200
  • Catalyst Ess9300
  • Catalyst Ie9310
  • Catalyst Ie9320
  • Ie3500
  • Ie3505
  • *
  • *
  • *
  • *
  • *
  • *

Weaknesses

Common security weaknesses mapped to this vulnerability.

CWE-124
Buffer Underwrite ('Buffer Underflow')
The product writes to a buffer using an index or pointer that references a memory location prior to the beginning of the buffer.

*CPE(s)

Affected systems and software identified for this CVE.

Type Vendor Product Version Update Edition Language Software Edition Target Software Target Hardware Other Information
h cisco catalyst_9200 / / / / / / / /
h cisco catalyst_ess9300 / / / / / / / /
h cisco catalyst_ie9310 / / / / / / / /
h cisco catalyst_ie9320 / / / / / / / /
h cisco ie3500 / / / / / / / /
h cisco ie3505 / / / / / / / /

References

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

Tags

CWE-124
[email protected]
2026-03-25
CVE-2026-20104

CVSS Score

6.1 / 10

CVSS Data - 3.1

  • Attack Vector: PHYSICAL
  • Attack Complexity: LOW
  • Privileges Required: NONE
  • Scope: UNCHANGED
  • Confidentiality Impact: HIGH
  • Integrity Impact: HIGH
  • Availability Impact: NONE

    • CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:N

    View Vector String

Timeline

Published: March 25, 2026, 4:16 p.m.
Last Modified: March 26, 2026, 3:13 p.m.

Status : Awaiting Analysis

CVE has been recently published to the CVE List and has been received by the NVD.

More info

Source

[email protected]

*Disclaimer: Some vulnerabilities do not have an associated CPE. To enhance the data, we use AI to infer CPEs based on CVE details. This is an automated process and might not always be accurate.