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Adaptive Security Appliance SoftwareOperating system · Cisco

CVE-2026-20106

MEDIUM · 5.3 CVSS v3.1 Published 2026-03-04
Fix available
A fix is available. Upgrade to 7.0.9 / 7.2.11 or later.
See remediation →
62/100
Remediation priority · Elevated
Remotely reachable No privileges 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 Remote Access SSL VPN, HTTP management and MUS functionality, of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to exhaust device memory resulting in a denial of service (DoS) condition requiring a manual reboot. This vulnerability is due to trusting user input without validation. An attacker could exploit this vulnerability by sending crafted packets to the Remote Access SSL VPN server. A successful exploit could allow the attacker to cause the device to stop responding, resulting in a DoS condition.

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 · moderate confidence

This is a memory exhaustion denial-of-service vulnerability in Cisco ASA and FTD firewall software affecting the Remote Access SSL VPN, HTTP management, and MUS functionality. The vulnerability stems from improper validation of user input in crafted packets sent to the SSL VPN server, allowing an unauthenticated remote attacker to cause memory exhaustion that crashes the device and requires manual reboot to recover.

MitigationApply the vendor-supplied patches from Cisco for ASA and FTD software. Until patches are available, consider implementing rate limiting on VPN interfaces and restricting management access to trusted networks.

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:>= 9.12.1, < 9.16.4.85>= 9.17.1, < 9.18.4.66>= 9.19.1, < 9.20.4>= 9.22.1.1, < 9.22.2.4>= 9.23.1, < 9.23.1.7
Secure Firewall Threat DefenseApplication
Affected:>= 6.4.0, < 7.0.9>= 7.1.0, < 7.2.11>= 7.3.0, < 7.4.3>= 7.6.0, < 7.6.4>= 7.7.0, < 7.7.11

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
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

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

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 Cisco device type and version
    For ASA devices, run 'show version | include Version' at the CLI. For FTD devices, run 'show version' or access the FTD management center to view the software version.
    Affected if The device runs Cisco ASA Software version 9.12.1 through 9.16.4.84, 9.17.1 through 9.18.4.65, 9.19.1 through 9.20.3, 9.22.1.1 through 9.22.2.3, or 9.23.1 through 9.23.1.6; OR Cisco FTD Software version 6.4.0 through 7.0.8, 7.1.0 through 7.2.10, 7.3.0 through 7.4.2, 7.6.0 through 7.6.3, or 7.7.0 thr
  2. Verify if SSL VPN is enabled
    Run 'show vpn-sessiondb' or 'show webvpn session' at the ASA/FTD CLI to check for active or configured SSL VPN sessions.
    Affected if SSL VPN (AnyConnect or clientless) is configured or active on the device, as the vulnerability is triggered through packets sent to the SSL VPN server.
  3. Check HTTP management interface exposure
    Run 'show run | include http' to display HTTP management access configuration.
    Affected if HTTP management is enabled (via 'http <ip> <mask> <interface>' command) and accessible from untrusted networks, as this is one of the affected interfaces.
  4. Check MUS (Management User Service) exposure
    Run 'show run all mus' or review the configuration for any MUS-related settings.
    Affected if MUS functionality is enabled and reachable, as this is listed as an affected functionality path.

A device is affected if it runs a vulnerable ASA or FTD version AND has SSL VPN, HTTP management, or MUS exposed to network traffic where an attacker could send crafted packets.

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 7.0.9 / 7.2.11 / 7.4.3 or later
Fixed in 7.0.97.2.117.4.3
Interim mitigation

Apply the vendor-supplied patches from Cisco for ASA and FTD software. Until patches are available, consider implementing rate limiting on VPN interfaces and restricting management access to trusted networks.

Recommended fix High confidence

ASA: upgrade to 9.16.4.85, 9.18.4.66, 9.20.4, or 9.22.2.4 or later (latest recommended: 9.22.2.4+); FTD: upgrade to 7.0.9, 7.2.11, 7.4.3, or 7.6.4 or later (latest recommended: 7.6.4+)

  1. 1. Identify the current Cisco ASA or FTD software version by running 'show version' on the device CLI
  2. 2. Determine which software branch (ASA 9.16, 9.18, 9.20, 9.22 or FTD 7.0, 7.2, 7.4, 7.6) matches your current version
  3. 3. Download the appropriate fixed software release from Cisco (see upgrade_path)
  4. 4. Back up the current device configuration using 'write mem' or through the management interface
  5. 5. Upload the new software image to the device using 'copy' command or via the management interface
  6. 6. Perform a software upgrade using the 'reload' command after installing the new image
  7. 7. Verify the device comes back online with the new version using 'show version'
  8. 8. Confirm the vulnerability is remediated by checking that memory usage remains stable under normal operation
Caveat Standard Cisco upgrade precautions apply: ensure compatibility with existing VPN configurations, check release notes for any behavior changes, and plan maintenance window as upgrade will cause brief outage

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

Fix this in Adaptive Security Appliance Software Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2026-20106 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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