{"cve":"CVE-2021-1224","nvd":{"published":"2021-01-13T22:15:20.410","modified":"2026-08-11T19:37:30.880","status":"Modified","description":"Multiple Cisco products are affected by a vulnerability with TCP Fast Open (TFO) when used in conjunction with the Snort detection engine that could allow an unauthenticated, remote attacker to bypass a configured file policy for HTTP. The vulnerability is due to incorrect detection of the HTTP payload if it is contained at least partially within the TFO connection handshake. An attacker could exploit this vulnerability by sending crafted TFO packets with an HTTP payload through an affected device. A successful exploit could allow the attacker to bypass configured file policy for HTTP packets and deliver a malicious payload.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N","score":5.3},"cwes":["CWE-693"],"references":["https://lists.debian.org/debian-lts-announce/2023/02/msg00011.html","https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort-tfo-bypass-MmzZrtes","https://www.debian.org/security/2023/dsa-5354","https://lists.debian.org/debian-lts-announce/2023/02/msg00011.html","https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-snort-tfo-bypass-MmzZrtes"],"products":["cisco:ios_xe","cisco:meraki_mx100_firmware","cisco:meraki_mx250_firmware","cisco:meraki_mx450_firmware","cisco:meraki_mx64_firmware","cisco:meraki_mx64w_firmware","cisco:meraki_mx67_firmware","cisco:meraki_mx67c_firmware","cisco:meraki_mx67w_firmware","cisco:meraki_mx68_firmware","cisco:meraki_mx68cw_firmware","cisco:meraki_mx68w_firmware","cisco:meraki_mx84_firmware","cisco:secure_firewall_management_center","cisco:secure_firewall_threat_defense","snort:snort"],"source":"nvd","synced_at":"2026-10-19T21:14:10.479542811+00:00"},"epss":{"cve":"CVE-2021-1224","score":0.02046,"percentile":0.81203,"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."]}