CVE-2026-20021
A vulnerability in the OSPF protocol of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an authenticated, adjacent attacker to exhaust memory on an affected device, resulting in a denial of service (DoS) condition. This vulnerability is due to improperly validating input by the OSPF protocol when parsing packets. An attacker could exploit this vulnerability by by sending crafted OSPF packets to an affected device. A successful exploit could allow the attacker to exhaust memory on the affected device, resulting in a DoS condition.
EPSS 0.01% · 0.7th percentile
Risk Scores
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Cisco | Cisco Secure Firewall Threat Defense (FTD) Software | 6.4.0.2, 6.4.0, 6.4.0.1 |
| Cisco | Cisco Secure Firewall Adaptive Security Appliance (ASA) Software | 9.12.1, 9.12.1.2, 9.12.1.3 |
Exploit Intelligence
- CIRCL seen: CVE-2026-20021 (circl-sighting)
- cisco-sa-asaftd-ospf-ZH8PhbSW (circl)
Timeline
- Oct 8, 2025 CVE ID Reserved
- Mar 4, 2026 CVE Published
- Mar 4, 2026 PoC Published
- Mar 4, 2026 CVE Updated
- Mar 5, 2026 EPSS Score
- Mar 6, 2026 EPSS Score
- Mar 7, 2026 EPSS Score
- Mar 9, 2026 EPSS Score
- Mar 10, 2026 EPSS Score
- Mar 11, 2026 EPSS Score
- Mar 12, 2026 EPSS Score
- Mar 14, 2026 EPSS Score