CVE-2021-1224: Cisco IOS XE
Medium severity, CVSS 5.3. EPSS: 2% chance of exploitation in the next 30 days.
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.
Affected products
- Cisco IOS XE: before 17.4.1 (fixed in 17.4.1)
- Cisco Meraki MX100 Firmware: affected versions not specified
- Cisco Meraki MX250 Firmware: affected versions not specified
- Cisco Meraki MX450 Firmware: affected versions not specified
- Cisco Meraki MX64 Firmware: affected versions not specified
- Cisco Meraki MX64W Firmware: affected versions not specified
- Cisco Meraki MX67 Firmware: affected versions not specified
- Cisco Meraki MX67C Firmware: affected versions not specified
- Cisco Meraki MX67W Firmware: affected versions not specified
- Cisco Meraki MX68 Firmware: affected versions not specified
- Cisco Meraki MX68CW Firmware: affected versions not specified
- Cisco Meraki MX68W Firmware: affected versions not specified
- Cisco Meraki MX84 Firmware: affected versions not specified
- Cisco Secure Firewall Management Center: version 2.9.14.0 only; version 2.9.15 only; version 2.9.16 only; version 2.9.17 only; version 2.9.18 only; version 3.0.1 only
- Cisco Secure Firewall Threat Defense: before 6.7.0 (fixed in 6.7.0)
- Snort Snort: before 2.9.17 (fixed in 2.9.17)
Published 2021-01-13. Last modified 2026-08-11.