CVE-2020-3421: Cisco IOS XE Software Zone-Based Firewall Denial of Service Vulnerabilities
First published: Thu Sep 24 2020(Updated: )
Multiple vulnerabilities in the Zone-Based Firewall feature of Cisco IOS XE Software could allow an unauthenticated, remote attacker to cause the device to reload or stop forwarding traffic through the firewall. The vulnerabilities are due to incomplete handling of Layer 4 packets through the device. An attacker could exploit these vulnerabilities by sending a certain sequence of traffic patterns through the device. A successful exploit could allow the attacker to cause the device to reload or stop forwarding traffic through the firewall, resulting in a denial of service. For more information about these vulnerabilities, see the Details section of this advisory.
Credit: ykramarz@cisco.com
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Cisco IOS XE | =16.9.3 | |
| Cisco 4221 Integrated Services Router | ||
| Cisco 4321 Integrated Services Router | ||
| Cisco 4331 Integrated Services Router | ||
| Cisco 4351 Integrated Services Router | ||
| Cisco 4431 Integrated Services Router | ||
| Cisco 4461 Integrated Services Router | ||
| Cisco Asr 1001-hx | ||
| Cisco Asr 1001-x | ||
| Cisco Asr 1002-hx | ||
| Cisco Asr 1002-x | ||
| Cisco Asr 1004 | ||
| Cisco Asr 1006 | ||
| Cisco Asr 1006-x | ||
| Cisco Asr 1009-x | ||
| Cisco Asr 1013 | ||
| Cisco IOS XE | =17.2 | |
| Cisco 1100 Integrated Services Router | ||
| Cisco 1101 Integrated Services Router | ||
| Cisco 1109 Integrated Services Router | ||
| Cisco 1111x Integrated Services Router | ||
| Cisco 111x Integrated Services Router | ||
| Cisco 1120 Integrated Services Router | ||
| Cisco 1160 Integrated Services Router | ||
| Cisco Csr 1000v |
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Reference Links
Frequently Asked Questions
What is CVE-2020-3421?
CVE-2020-3421 is a vulnerability in the Zone-Based Firewall feature of Cisco IOS XE Software that can allow an unauthenticated, remote attacker to cause the device to reload or stop forwarding traffic through the firewall.
How severe is CVE-2020-3421?
CVE-2020-3421 has a severity rating of 7.5, which is considered high.
Which software versions are affected by CVE-2020-3421?
Cisco IOS XE Software version 16.9.3 and 17.2 are affected by CVE-2020-3421.
How can I fix CVE-2020-3421?
To fix CVE-2020-3421, Cisco recommends upgrading to a fixed software release.
Where can I find more information about CVE-2020-3421?
You can find more information about CVE-2020-3421 on the Cisco Security Advisory page: [link](https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-zbfw-94ckG4G)
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- agent/type
- agent/softwarecombine
- collector/mitre-cve
- source/MITRE
- agent/references
- agent/severity
- agent/title
- agent/last-modified-date
- agent/weakness
- agent/author
- agent/tags
- agent/description
- agent/first-publish-date
- agent/event
- vendor/cisco
- canonical/cisco ios xe
- version/cisco ios xe/16.9.3
- canonical/cisco 4221 integrated services router
- canonical/cisco 4321 integrated services router
- canonical/cisco 4331 integrated services router
- canonical/cisco 4351 integrated services router
- canonical/cisco 4431 integrated services router
- canonical/cisco 4461 integrated services router
- canonical/cisco asr 1001-hx
- canonical/cisco asr 1001-x
- canonical/cisco asr 1002-hx
- canonical/cisco asr 1002-x
- canonical/cisco asr 1004
- canonical/cisco asr 1006
- canonical/cisco asr 1006-x
- canonical/cisco asr 1009-x
- canonical/cisco asr 1013
- version/cisco ios xe/17.2
- canonical/cisco 1100 integrated services router
- canonical/cisco 1101 integrated services router
- canonical/cisco 1109 integrated services router
- canonical/cisco 1111x integrated services router
- canonical/cisco 111x integrated services router
- canonical/cisco 1120 integrated services router
- canonical/cisco 1160 integrated services router
- canonical/cisco csr 1000v