{"id":"CVE-2021-1453","url":"https://www.cyber-defence.io/tools/cve/CVE-2021-1453","generatedAt":"2026-10-27T22:31:50.838Z","title":"A vulnerability in the software image verification functionality of Cisco IOS XE Software for the Cisco Catalyst 9000 Family of switches could allow an unauthenticated, physical attacker to execute unsigned code at system boot time.","description":"A vulnerability in the software image verification functionality of Cisco IOS XE Software for the Cisco Catalyst 9000 Family of switches could allow an unauthenticated, physical attacker to execute unsigned code at system boot time. The vulnerability is due to an improper check in the code function that manages the verification of the digital signatures of system image files during the initial boot process. An attacker could exploit this vulnerability by loading unsigned software on an affected device. A successful exploit could allow the attacker to boot a malicious software image or execute unsigned code and bypass the image verification check part of the secure boot process of an affected device. To exploit this vulnerability, the attacker would need to have unauthenticated physical access to the device or obtain privileged access to the root shell on the device.","published":"2021-03-24T20:15:16.000Z","lastModified":"2026-06-17T03:31:49.000Z","status":"Modified","sourceIdentifier":"psirt@cisco.com","cvss":{"version":"3.1","score":6.8,"severity":"MEDIUM","vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"},"cwe":["CWE-347"],"affected":["cisco/ios xe"],"epss":{"score":0.00231,"percentile":0.13882,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.23%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xe-cat-verify-BQ5hrXgH","tags":["Vendor Advisory"],"source":"psirt@cisco.com"},{"url":"https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xe-cat-verify-BQ5hrXgH","tags":["Vendor Advisory"],"source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2021-1453","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}