{"cve":"CVE-2021-1453","nvd":{"published":"2021-03-24T20:15:15.623","modified":"2026-06-17T03:31:48.803","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":6.8},"cwes":["CWE-347"],"references":["https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xe-cat-verify-BQ5hrXgH","https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ios-xe-cat-verify-BQ5hrXgH"],"products":["cisco:ios_xe"],"source":"nvd","synced_at":"2026-10-19T21:15:50.279857260+00:00"},"epss":{"cve":"CVE-2021-1453","score":0.00231,"percentile":0.14064,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}