CVE-2021-1224

What it is

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.

At a glance

Exploitability

Can be exploited over the network without logging in. Limited direct impact.

Exploit odds

2.0% chance of exploitation in the next 30 days (EPSS).

Fix

A patch, advisory or fixed version is referenced. Upgrade or apply it.

Timeline

1. 2021-01-13 22:15 UTC PublishedDisclosed publicly on CVE.org and NVD
2. 2026-08-11 19:37 UTC Last updatedMost recent change to the record

Why it ranks here

• Exploited in the wild: no, CISA does not list it.
• Exploit odds: 2.0% in the next 30 days (EPSS).
• Severity: 5.8 MEDIUM (CVSS).
• Fix: a patch or advisory is linked.

Details

Published

2021-01-13 22:15 UTC

Last modified

2026-08-11 19:37 UTC

Exploit probability

2.0% · EPSS, next 30 days

Weakness

CWE-693

Record status

Modified

Affected

• Cisco Secure Firewall Management Center 2.9.14.0
• Cisco Secure Firewall Management Center 2.9.15
• Cisco Secure Firewall Management Center 2.9.16
• Cisco Secure Firewall Management Center 2.9.17
• Cisco Secure Firewall Management Center 2.9.18
• Cisco Secure Firewall Management Center 3.0.1
• Cisco Secure Firewall Threat Defense < 6.7.0
• Cisco iOS Xe < 17.4.1

Attack profile CVSS 3.1 · 5.8

Attack vector

Network

Complexity

Low

Privileges needed

None

User interaction

None

Scope

Changed

Confidentiality

None

Integrity

Low

Availability

None

Is it in your code?

Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.

Read https://cve-list.com/agent/cve/CVE-2021-1224.md and follow it. Check whether this project is affected by CVE-2021-1224. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.

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