Medium severity · published Mar 4, 2026
CVE-2026-20020
A vulnerability in the OSPF protocol of Cisco Secure Firewall ASA Software and Cisco Secure FTD Software could allow an unauthenticated, adjacent attacker to cause an affected…
5.7
CVSS
0.2%
EPSS
No
On KEV
Description
A vulnerability in the OSPF protocol of Cisco Secure Firewall ASA Software and Cisco Secure FTD Software could allow an unauthenticated, adjacent attacker to cause an affected device to reload unexpectedly, resulting in a DoS condition. If OSPF authentication is enabled, the attacker must know the secret key to exploit this vulnerability.
This vulnerability is due to insufficient input validation when processing OSPF update packets. An attacker could exploit this vulnerability by sending crafted OSPF update packets. A successful exploit could allow the attacker to create a buffer overflow, causing the affected device to reload, resulting in a DoS condition.
CVSS vector
CVSS:3.1/AV:A/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Attack vector
Adjacent
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
None
Integrity
None
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 16% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
CS
Cisco Secure Firewall Adaptive Security Appliance (ASA) Software · Cisco
9.12.1; 9.12.1.2; 9.12.1.3; 9.12.2; 9.12.2.4; 9.12.2.5; +34 more · source: vendor
CS
Cisco Secure Firewall Threat Defense (FTD) Software · Cisco
6.4.0; 6.4.0.1; 6.4.0.3; 6.4.0.2; 6.4.0.4; 6.4.0.5; +34 more · source: vendor
AS
Adaptive Security Appliance Software · Cisco
9.12.1; 9.12.1.2; 9.12.1.3; 9.12.2; 9.12.2.1; 9.12.2.4; +34 more · source: NVD
SF
Secure Firewall Threat Defense · Cisco
6.4.0; 6.4.0.1; 6.4.0.2; 6.4.0.3; 6.4.0.4; 6.4.0.5; +34 more · source: NVD
Affected product
CS
Cisco Secure Firewall Adaptive Security Appliance (ASA) Software
Cisco
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-20020
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-20020
Vendor Advisory
https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ospf-ZH8PhbSW
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