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Adaptive Security Appliance SoftwareOperating system · Cisco

CVE-2026-20049

HIGH · 7.7 CVSS v3.1 Published 2026-03-04
Fix available
A fix is available. Upgrade to 7.2.11 / 7.4.3 or later.
See remediation →
83/100
Remediation priority · High
Remotely reachable Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability in the processing of Galois/Counter Mode (GCM)-encrypted Internet Key Exchange version 2 (IKEv2) IPsec traffic of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Cisco Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to the allocation of an insufficiently sized block of memory. An attacker could exploit this vulnerability by sending crafted GCM-encrypted IPsec traffic to an affected device. A successful exploit could allow the attacker to cause an unexpected reload of the device, resulting in a DoS condition. To exploit this vulnerability, the attacker must have valid credentials to establish a VPN connection with the affected device.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

A memory allocation vulnerability exists in Cisco ASA and FTD software when processing GCM-encrypted IKEv2 IPsec traffic. The insufficiently sized memory block causes a buffer overflow condition when processing specially crafted GCM-encrypted packets, leading to an unexpected device reload and denial of service.

MitigationApply the relevant Cisco software update (patch) for ASA or FTD when released. Until then, limit VPN access to trusted users and monitor for unusual IPsec traffic patterns.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Adaptive Security Appliance SoftwareOperating system
Affected:>= 9.18.1, < 9.18.4.66>= 9.19.1, < 9.20.3.20>= 9.22.1.1, < 9.22.2.4>= 9.23.1, < 9.23.1.3
Secure Firewall Threat DefenseApplication
Affected:>= 7.2.0, < 7.2.11>= 7.3.0, < 7.4.3>= 7.6.0, < 7.6.4>= 7.7.0, < 7.7.10

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:N/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the device product type
    Run 'show version' or access the device management interface to confirm whether the device runs Cisco ASA Software or Cisco Firepower Threat Defense (FTD) Software.
    Affected if The device runs ASA or FTD software.
  2. Check the installed ASA software version
    Execute 'show version' on the ASA CLI and locate the running software version number (for example, 9.18.x or 9.22.x).
    Affected if The ASA version falls within these ranges: 9.18.1 to 9.18.4.65, 9.19.1 to 9.20.3.19, 9.22.1.1 to 9.22.2.3, or 9.23.1 to 9.23.1.2.
  3. Check the installed FTD software version
    Execute 'show version' on the FTD device (or check via FMC management) and locate the running software version number (for example, 7.3.x or 7.6.x).
    Affected if The FTD version falls within these ranges: 7.2.0 to 7.2.10, 7.3.0 to 7.4.2, 7.6.0 to 7.6.3, or 7.7.0 to 7.7.9.
  4. Verify if IKEv2 VPN with GCM encryption is configured
    Run 'show crypto ipsec sa' and 'show crypto ikev2 sa detail' to inspect active IPsec security associations; check the encryption algorithm listed (look for AES-GCM or GCM variants in the transform set or crypto map).
    Affected if IKEv2 VPN tunnels are active and using GCM (AES-GCM) encryption for IPsec.
  5. Check for GCM-based IKEv2 crypto maps or policies
    Run 'show run crypto map' and inspect the transform-set definitions; look for 'esp-aes-gcm' or 'esp-aes-256-gcm' in the configuration.
    Affected if Crypto maps or IKEv2 proposals are configured using GCM encryption algorithms.

The device is affected if it runs Cisco ASA or FTD software within the listed version ranges AND has IKEv2 VPN tunnels or crypto policies using GCM encryption configured.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 7.2.11 / 7.4.3 / 7.6.4 or later
Fixed in 7.2.117.4.37.6.4
Interim mitigation

Apply the relevant Cisco software update (patch) for ASA or FTD when released. Until then, limit VPN access to trusted users and monitor for unusual IPsec traffic patterns.

Recommended fix High confidence

ASA: 9.18.4.66, 9.20.3.20, 9.22.2.4, or 9.23.1.3 (depending on current branch); FTD: 7.2.11, 7.4.3, 7.6.4, or 7.7.10 (depending on current branch)

  1. 1. Identify the current Cisco ASA or FTD software version using 'show version' command
  2. 2. Determine the appropriate upgrade path based on the current version (see upgrade_path field)
  3. 3. Download the fixed software version from Cisco's official download page at sec.cloudapps.cisco.com
  4. 4. Back up the current device configuration
  5. 5. Upload the new software image to the device using 'copy' command or through the management interface
  6. 6. Schedule a maintenance window as the upgrade will require a device reload
  7. 7. Install the new image using 'install' command or via the web interface
  8. 8. Verify the upgrade completed successfully using 'show version' to confirm the new version is running
Caveat Standard Cisco upgrade precautions apply - ensure configuration backup and plan for brief downtime during reload

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Adaptive Security Appliance Software Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing8.0 h
  • Review / QA4.0 h
20.0 hours of engineering $3,440
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An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,504.

Scan for this in your stack

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-20049 in production — separate from our analysis above.

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What this is

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What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
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