Is CVE-2026-20049 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-20049 being exploited in the wild.

How severe is CVE-2026-20049?

High severity, with a CVSS score of 7.7, published 4 March 2026.

Which products and versions are affected?

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software Multiple versions; see vendor advisory for affected releases; Cisco Secure Firewall Threat Defense (FTD) Software Multiple versions; see vendor advisory for affected releases.

Is there a fix for CVE-2026-20049?

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-2026-20049 attacked?

It is attacked over the network, in a network appliance.

Am I affected by CVE-2026-20049?

Check whether you run Cisco Secure Firewall Adaptive Security Appliance (ASA) Software or Cisco Secure Firewall Threat Defense (FTD) 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-2026-20049: Cisco Secure Firewall IPsec GCM buffer overflow denial of service

CVE-2026-20049 · Severity: high · CVSS 7.7 · Published 2026-03-04

Cisco Secure Firewall devices (ASA and FTD) used to protect networks and enforce security policies contain a memory allocation flaw in IPsec encryption processing. An authenticated attacker with VPN credentials can send specially crafted encrypted traffic to crash the firewall, causing service outages and disrupting network connectivity and security enforcement.

Technologies: Cisco Secure Firewall Adaptive Security Appliance (ASA) Software, Cisco Secure Firewall Threat Defense (FTD) Software. Vendors: Cisco.

Quick answers

Is CVE-2026-20049 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-20049 being exploited in the wild.
How severe is CVE-2026-20049?: High severity, with a CVSS score of 7.7, published 4 March 2026.
Which products and versions are affected?: Cisco Secure Firewall Adaptive Security Appliance (ASA) Software Multiple versions; see vendor advisory for affected releases; Cisco Secure Firewall Threat Defense (FTD) Software Multiple versions; see vendor advisory for affected releases.
Is there a fix for CVE-2026-20049?: 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-2026-20049 attacked?: It is attacked over the network, in a network appliance.
Am I affected by CVE-2026-20049?: Check whether you run Cisco Secure Firewall Adaptive Security Appliance (ASA) Software or Cisco Secure Firewall Threat Defense (FTD) 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

This vulnerability is an insufficient buffer allocation flaw (CWE-131) in the processing of Galois/Counter Mode (GCM)-encrypted IKEv2 IPsec traffic. When a Cisco Secure Firewall ASA or FTD device is configured with GCM encryption for IPsec IKEv2 proposals (aes-gcm, aes-gcm-192, or aes-gcm-256), the device allocates an undersized memory block to handle incoming encrypted traffic. An authenticated attacker with valid VPN credentials can exploit this by sending crafted GCM-encrypted IPsec packets to the device, triggering a buffer overflow that causes an unexpected device reload (denial of service). Exploitation requires network access to the VPN endpoint and valid authentication credentials. Cisco has released fixed software versions; no workarounds are available.

Affected products

Cisco Secure Firewall Adaptive Security Appliance (ASA) Software Multiple versions; see vendor advisory for affected releases
Cisco Secure Firewall Threat Defense (FTD) Software Multiple versions; see vendor advisory for affected releases

Timeline

2026-03-04: disclosed: Cisco security advisory published

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asaftd-esp-dos-uv7yD8P5

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