CVE-2020-3421 : Multiple vulnerabilities in the Zone-Based Firewall feature of Cisco IOS XE Soft

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.

Published 2020-09-24 18:15:19

Updated 2023-05-22 18:57:25

Source Cisco Systems, Inc.

View at NVD, CVE.org

Vulnerability category: Denial of service

Products affected by CVE-2020-3421

Cisco » Ios Xe » Version: 16.9.3
cpe:2.3:o:cisco:ios_xe:16.9.3:*:*:*:*:*:*:*
Matching versions
When used together with: Cisco » 4221 Integrated Services Router » Version: N/A
When used together with: Cisco » 4321 Integrated Services Router » Version: N/A
When used together with: Cisco » 4331 Integrated Services Router » Version: N/A
When used together with: Cisco » 4351 Integrated Services Router » Version: N/A
When used together with: Cisco » 4431 Integrated Services Router » Version: N/A
When used together with: Cisco » 4461 Integrated Services Router » Version: N/A
When used together with: Cisco » Asr 1001-hx » Version: N/A
When used together with: Cisco » Asr 1001-x » Version: N/A
When used together with: Cisco » Asr 1002-hx » Version: N/A
When used together with: Cisco » Asr 1002-x » Version: N/A
When used together with: Cisco » Asr 1004 » Version: N/A
When used together with: Cisco » Asr 1006 » Version: N/A
When used together with: Cisco » Asr 1006-x » Version: N/A
When used together with: Cisco » Asr 1009-x » Version: N/A
When used together with: Cisco » Asr 1013 » Version: N/A
Cisco » Ios Xe » Version: 17.2
cpe:2.3:o:cisco:ios_xe:17.2:*:*:*:*:*:*:*
Matching versions
When used together with: Cisco » 1100 Integrated Services Router » Version: N/A
When used together with: Cisco » 1101 Integrated Services Router » Version: N/A
When used together with: Cisco » 1109 Integrated Services Router » Version: N/A
When used together with: Cisco » 1111x Integrated Services Router » Version: N/A
When used together with: Cisco » 111x Integrated Services Router » Version: N/A
When used together with: Cisco » 1120 Integrated Services Router » Version: N/A
When used together with: Cisco » 1160 Integrated Services Router » Version: N/A
When used together with: Cisco » 4221 Integrated Services Router » Version: N/A
When used together with: Cisco » 4331 Integrated Services Router » Version: N/A
When used together with: Cisco » 4431 Integrated Services Router » Version: N/A
When used together with: Cisco » 4461 Integrated Services Router » Version: N/A
When used together with: Cisco » Asr 1001-hx » Version: N/A
When used together with: Cisco » Asr 1001-x » Version: N/A
When used together with: Cisco » Asr 1002-hx » Version: N/A
When used together with: Cisco » Asr 1002-x » Version: N/A
When used together with: Cisco » Asr 1004 » Version: N/A
When used together with: Cisco » Asr 1006 » Version: N/A
When used together with: Cisco » Asr 1006-x » Version: N/A
When used together with: Cisco » Asr 1009-x » Version: N/A
When used together with: Cisco » Asr 1013 » Version: N/A
When used together with: Cisco » Csr 1000v » Version: N/A

Exploit prediction scoring system (EPSS) score for CVE-2020-3421

EPSS FAQ

0.16%

Probability of exploitation activity in the next 30 days EPSS Score History

~ 52 %

Percentile, the proportion of vulnerabilities that are scored at or less

CVSS scores for CVE-2020-3421

Base Score	Base Severity	CVSS Vector	Exploitability Score	Impact Score	Score Source
7.1	HIGH	AV:N/AC:M/Au:N/C:N/I:N/A:C	8.6	6.9	NIST
Access Vector: Network Access Complexity: Medium Authentication: None Confidentiality Impact: None Integrity Impact: None Availability Impact: Complete
8.6	HIGH	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H	3.9	4.0	Cisco Systems, Inc.
Attack Vector: Network Attack Complexity: Low Privileges Required: None User Interaction: None Scope: Changed Confidentiality: None Integrity: None Availability: High
7.5	HIGH	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H	3.9	3.6	NIST
Attack Vector: Network Attack Complexity: Low Privileges Required: None User Interaction: None Scope: Unchanged Confidentiality: None Integrity: None Availability: High

CWE ids for CVE-2020-3421

CWE-754 Improper Check for Unusual or Exceptional Conditions

The product does not check or incorrectly checks for unusual or exceptional conditions that are not expected to occur frequently during day to day operation of the product.
Assigned by:
- nvd@nist.gov (Primary)
- ykramarz@cisco.com (Secondary)

References for CVE-2020-3421

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-zbfw-94ckG4G

Cisco IOS XE Software Zone-Based Firewall Denial of Service Vulnerabilities
Vendor Advisory

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Vulnerability Details : CVE-2020-3421

Products affected by CVE-2020-3421

Exploit prediction scoring system (EPSS) score for CVE-2020-3421

CVSS scores for CVE-2020-3421

CWE ids for CVE-2020-3421

References for CVE-2020-3421