{"id":"CVE-2021-34753","aliases":["EUVD-2021-21403","GHSA-4383-m935-j5wh"],"status":"published","title":"Cisco Firepower Threat Defense Ethernet Industrial Protocol Policy Bypass Vulnerabilities","description":"A vulnerability in the payload inspection for Ethernet Industrial Protocol (ENIP) traffic for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured rules for ENIP traffic.\r\n\r\nThis vulnerability is due to incomplete processing during deep packet inspection for ENIP packets. An attacker could exploit this vulnerability by sending a crafted ENIP packet to the targeted interface. A successful exploit could allow the attacker to bypass configured access control and intrusion policies that should trigger and drop for the ENIP packet.","severity":{"version":"3.1","score":5.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","level":"medium","assessor":"cna","from":"cve"},"epss":{"day":"2026-11-10","score":0.00663,"percentile":0.52023,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":false},"cwes":["CWE-284"],"published":"2024-11-15T16:14:45Z","modified":"2026-08-11T19:40:47Z","products":[{"vendor":"cisco","product":"cisco firepower threat defense software"},{"vendor":"cisco","product":"firepower_threat_defense_software"},{"vendor":"cisco","product":"secure_firewall_threat_defense"}],"references":[{"url":"https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-ftd-enip-bypass-eFsxd8KP","tags":["Vendor Advisory"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-34753"},{"url":"https://github.com/advisories/GHSA-4383-m935-j5wh"}],"sources":{"cve":[{"id":"CVE-2021-34753","title":"Cisco Firepower Threat Defense Ethernet Industrial Protocol Policy Bypass Vulnerabilities","description":"A vulnerability in the payload inspection for Ethernet Industrial Protocol (ENIP) traffic for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured rules for ENIP traffic.\r\n\r\nThis vulnerability is due to incomplete processing during deep packet inspection for ENIP packets. An attacker could exploit this vulnerability by sending a crafted ENIP packet to the targeted interface. A successful exploit could allow the attacker to bypass configured access control and intrusion policies that should trigger and drop for the ENIP packet.","status":"published","published":"2024-11-15T16:14:45.327Z","modified":"2024-11-15T18:06:40.214Z","cvss":[{"version":"3.1","score":5.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","level":"medium","assessor":"cna"}],"cwes":["CWE-284"],"updated_at":"2026-11-02T14:33:11.59359Z"}],"euvd":[{"id":"EUVD-2021-21403","description":"A vulnerability in the payload inspection for Ethernet Industrial Protocol (ENIP) traffic for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured rules for ENIP traffic.\r\n\r\nThis vulnerability is due to incomplete processing during deep packet inspection for ENIP packets. An attacker could exploit this vulnerability by sending a crafted ENIP packet to the targeted interface. A successful exploit could allow the attacker to bypass configured access control and intrusion policies that should trigger and drop for the ENIP packet.","status":"published","published":"2024-11-15T16:14:45Z","modified":"2024-11-15T18:06:40Z","cvss":[{"version":"3.1","score":5.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","level":"medium"}],"updated_at":"2026-11-03T00:04:58.20762Z"}],"ghsa":[{"id":"GHSA-4383-m935-j5wh","title":"A vulnerability in the payload inspection for Ethernet Industrial Protocol (ENIP) traffic for...","description":"A vulnerability in the payload inspection for Ethernet Industrial Protocol (ENIP) traffic for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured rules for ENIP traffic.\n\nThis vulnerability is due to incomplete processing during deep packet inspection for ENIP packets. An attacker could exploit this vulnerability by sending a crafted ENIP packet to the targeted interface. A successful exploit could allow the attacker to bypass configured access control and intrusion policies that should trigger and drop for the ENIP packet.","status":"published","published":"2024-11-15T18:30:51Z","modified":"2024-11-15T18:30:59Z","cvss":[{"version":"3.1","score":5.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","level":"medium"}],"cwes":["CWE-284"],"updated_at":"2026-11-02T14:58:51.371243Z"}],"nvd":[{"id":"CVE-2021-34753","description":"A vulnerability in the payload inspection for Ethernet Industrial Protocol (ENIP) traffic for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to bypass configured rules for ENIP traffic.\r\n\r\nThis vulnerability is due to incomplete processing during deep packet inspection for ENIP packets. An attacker could exploit this vulnerability by sending a crafted ENIP packet to the targeted interface. A successful exploit could allow the attacker to bypass configured access control and intrusion policies that should trigger and drop for the ENIP packet.","status":"published","published":"2024-11-15T17:15:10.303Z","modified":"2026-08-11T19:40:47.23Z","cvss":[{"version":"3.1","score":5.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N","level":"medium","assessor":"secondary"},{"version":"3.1","score":5.3,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","level":"medium","assessor":"primary"}],"cwes":["CWE-284"],"updated_at":"2026-11-02T14:07:08.629518Z"}]}}