HOMEVULNERABILITIESCVE-2021-1224
MEDIUM

CVE-2021-1224

CWE-693Published: January 13, 2021· Updated: Jun 17, 2026

5.3
CVSS v3.1

Official 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.

NVD Source

Technical Analysis

CVE-2021-1224 can be exploited remotely over the network without requiring physical or adjacent access, significantly expanding the attack surface for threat actors.

The vulnerability requires no privileges and no user interaction, making it a prime target for automated exploitation campaigns and worm-like propagation.

CVSS v3.1 Vector Breakdown

Exploitability
Attack VectorNetwork
Attack ComplexityLow
Privileges Req.None
User InteractionNone
ScopeUnchanged
Impact
ConfidentialityNone
IntegrityLow
AvailabilityNone
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N

Affected Vendors & Products

Cisco42 product(s)
firepower threat defensesecure firewall management centerios xe1100-4p integrated services router1100-8p integrated services router1101-4p integrated services router1109-2p integrated services router1109-4p integrated services router1111x-8p integrated services router4221 integrated services router4321 integrated services router4331 integrated services router+30
snort1 product(s)
snort
Source: NVD CPE · 48 total CPE entries

Exploit & PoC Resources

NO KNOWN EXPLOITNo public exploit confirmed at this time
External links open in a new tab. Always verify in a controlled environment before use.

Official Patches & Advisories

All References (6)

Quick Facts

CVE IDCVE-2021-1224
CVSS Score5.3 / 10
SeverityMEDIUM
WeaknessCWE-693
CISA KEVNo
Affected2 vendor(s)
PublishedJan 13, 2021

Related CVEs (CWE-693)

Recommended Actions

  • Apply vendor patches immediately
  • Monitor CVE-2021-1224 in threat intel feeds
  • Review IDS/IPS signatures for exploitation attempts
Data sourced from NVD (NIST), CISA KEV, and EPSS (FIRST). Analysis generated by CTIWATCH.COM. CVE data is provided under the NVD usage policy.