{"cve":"CVE-2021-1398","nvd":{"published":"2021-03-24T20:15:14.213","modified":"2026-06-17T03:31:40.937","status":"Modified","description":"A vulnerability in the boot logic of Cisco IOS XE Software could allow an authenticated, local attacker with level 15 privileges or an unauthenticated attacker with physical access to execute arbitrary code on the underlying Linux operating system of an affected device. This vulnerability is due to incorrect validations of specific function arguments that are passed to the boot script. An attacker could exploit this vulnerability by tampering with a specific file, which an affected device would process during the initial boot process. On systems that are protected by the Unified Extensible Firmware Interface (UEFI) secure boot feature, a successful exploit could allow the attacker to execute unsigned code at boot time and bypass the image verification check in the secure boot process of the affected 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-489"],"references":["https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-XE-ACE-75K3bRWe","https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-XE-ACE-75K3bRWe"],"products":["cisco:ios_xe"],"source":"nvd","synced_at":"2026-10-19T21:15:50.279857260+00:00"},"epss":{"cve":"CVE-2021-1398","score":0.0039,"percentile":0.33172,"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."]}