CVE-2021-1224

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.

What this means for your business

It affects Cisco Secure Firewall Management Center. It matters if your company, or a supplier that handles your data, runs it.
An attacker can use it remotely, over a network, without a login, and without anyone at your company clicking anything.
FIRST's prediction model gives it a 2% chance of attack attempts being seen in the next 30 days, ranking above 79% of all known flaws.

What to do

1Check whether your company or your suppliers run Cisco Secure Firewall Management Center, and which version. The affected versions are listed further down this page.
2If you do, apply the vendor's fix. A patch or vendor advisory has been published.

Not sure if your company is exposed?

Fastnexa’s certified penetration testers can check whether attackers could use this flaw, or others like it, against your websites, apps and network. The full test is free for our first 10 founding clients until 31 December 2026.

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Scoring

CVSS: 5.8 (v3.1)
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
Weakness: CWE-693
Assigned by: psirt@cisco.com

Dates

Published: 2021-01-13
Last modified: 2026-08-11
Sources: NVD

Affected products

Cisco Secure Firewall Management Center2.9.14.0, 2.9.15, 2.9.16, 2.9.17, 2.9.18, 3.0.1
Cisco Secure Firewall Threat Defense- 6.7.0
Cisco Ios Xe- 17.4.1
Cisco 1100-4p Integrated Services Routerall versions
Cisco 1100-8p Integrated Services Routerall versions
Cisco 1101-4p Integrated Services Routerall versions
Cisco 1109-2p Integrated Services Routerall versions
Cisco 1109-4p Integrated Services Routerall versions
Cisco 1111x-8p Integrated Services Routerall versions
Cisco 4221 Integrated Services Routerall versions
Cisco 4321 Integrated Services Routerall versions
Cisco 4331 Integrated Services Routerall versions

As listed in the NVD configuration data. Not a statement about your estate.