CVE-2021-1223: Multiple Cisco products are affected by a vulnerability in the Snort detection engine that could allow an unauthenticated, remote attacker to bypass a...

Description

Multiple Cisco products are affected by a vulnerability in 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 handling of an HTTP range header. An attacker could exploit this vulnerability by sending crafted HTTP packets through an affected device. A successful exploit could allow the attacker to bypass configured file policy for HTTP packets and deliver a malicious payload.

Metrics

CVSS 3.1

7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N

EPSS Probability

1.98%

78.1th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-693

Affected Software

Vendor	Product	Versions
Cisco	Firepower Threat Defense	< 6.7.0
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	Ios Xe	< 17.4.1
Snort	Snort	< 2.9.17

References

Timeline

Published: Jan 13, 2021
Last Modified: Jun 17, 2026
Status: Modified

Frequently Asked Questions

What is CVE-2021-1223?

Multiple Cisco products are affected by a vulnerability in 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 handling of an HTTP range header. An attacker could exploit this vulnerability by sending crafted HTTP packets through an affected device. A successful exploit could allow the attacker to bypass configured file policy for HTTP packets and deliver a malicious payload.

How severe is CVE-2021-1223?

CVE-2021-1223 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.98% probability of exploitation in the next 30 days.

How do I fix CVE-2021-1223?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.