Is CVE-2026-20020 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-20020 being exploited in the wild.

How severe is CVE-2026-20020?

Medium severity, with a CVSS score of 6.8, published 4 March 2026.

Is there a fix for CVE-2026-20020?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-20020 attacked?

It is attacked from the adjacent network, in a network appliance.

Am I affected by CVE-2026-20020?

Check whether you run Cisco Secure Firewall ASA Software or Cisco Secure Firewall Threat Defense Software at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-20020: Cisco Secure Firewall ASA and FTD OSPF buffer overflow

CVE-2026-20020 · Severity: medium · CVSS 6.8 · Published 2026-03-04

Cisco Secure Firewall ASA and FTD are network security appliances that route traffic using the OSPF routing protocol. A vulnerability in OSPF packet processing could allow an attacker on an adjacent network to send malicious packets, causing the firewall to crash and become unavailable. This results in a denial of service that disrupts network traffic protection.

Technologies: Cisco Secure Firewall ASA Software, Cisco Secure Firewall Threat Defense Software. Vendors: Cisco.

Quick answers

Is CVE-2026-20020 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-20020 being exploited in the wild.
How severe is CVE-2026-20020?: Medium severity, with a CVSS score of 6.8, published 4 March 2026.
Which products and versions are affected?: Cisco Secure Firewall ASA Software <UNKNOWN>; Cisco Secure Firewall Threat Defense Software <UNKNOWN>.
Is there a fix for CVE-2026-20020?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-20020 attacked?: It is attacked from the adjacent network, in a network appliance.
Am I affected by CVE-2026-20020?: Check whether you run Cisco Secure Firewall ASA Software or Cisco Secure Firewall Threat Defense Software at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

CVE-2026-20020 is a buffer overflow vulnerability (CWE-119, CWE-787) in the OSPF protocol implementation of Cisco Secure Firewall ASA and FTD software. The vulnerability stems from insufficient input validation when processing OSPF update packets. An unauthenticated adjacent attacker can send crafted OSPF update packets to trigger a heap overflow, causing the affected device to reload and enter a denial-of-service (DoS) condition. If OSPF authentication is enabled, the attacker must know the authentication secret key. Cisco has released software updates; no workarounds are available.

Affected products

Cisco Secure Firewall ASA Software <UNKNOWN>
Cisco Secure Firewall Threat Defense Software <UNKNOWN>

Timeline

2026-03-04: disclosed

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-ospf-ZH8PhbSW

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