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Adaptive Security Appliance SoftwareOperating system · Cisco

CVE-2026-20105

HIGH · 7.7 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 →
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 Remote Access SSL VPN functionality of Cisco Secure Firewall Adaptive Security Appliance (ASA) Software and Secure Firewall Threat Defense (FTD) Software could allow an authenticated, remote attacker with a valid VPN connection to exhaust device memory resulting in a denial of service (DoS) condition.This does not affect the management or MUS interfaces. 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 reload, 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

A memory exhaustion vulnerability exists in Cisco ASA and FTD Remote Access SSL VPN where the device trusts user input without validation. An authenticated attacker with valid VPN credentials can send crafted packets to exhaust device memory, causing the device to reload and result in a denial of service.

MitigationApply the Cisco security patch for this vulnerability; in the meantime, implement VPN session limits and monitor for abnormal memory usage patterns on affected devices.

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
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. Determine installed ASA software version
    Run 'show version' or 'show version | include Version' on the ASA CLI to obtain the running software version.
    Affected if The installed version falls within any of these ranges: >= 9.12.1 and < 9.16.4.85; >= 9.17.1 and < 9.18.4.66; >= 9.19.1 and < 9.20.4; >= 9.22.1.1 and < 9.22.2.4; >= 9.23.1 and < 9.23.1.7
  2. Determine installed FTD software version
    Run 'show version' via FTD CLI or via FMC management interface to identify the Firepower Threat Defense version.
    Affected if The installed version falls within any of these ranges: >= 6.4.0 and < 7.0.9; >= 7.1.0 and < 7.2.11; >= 7.3.0 and < 7.4.3; >= 7.6.0 and < 7.6.4; >= 7.7.0 and < 7.7.11
  3. Verify SSL VPN Remote Access is configured
    Run 'show vpn-sessiondb' or 'show run webvpn' on ASA; for FTD, check the VPN configuration via FMC or run 'show vpn-sessiondb' to confirm active or configured SSL VPN remote access tunnels.
    Affected if Remote Access SSL VPN is enabled and users have valid VPN credentials, creating the attack surface for this vulnerability.
  4. Confirm authentication method for VPN access
    Review VPN configuration with 'show run tunnel-group' and check the authentication server settings to determine if local or external authentication is in use.
    Affected if The device accepts authenticated VPN users, which is required for the attacker to exploit this flaw.

The device is affected if it runs a vulnerable ASA or FTD version within the listed ranges AND has Remote Access SSL VPN enabled with valid user authentication possible.

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 Cisco security patch for this vulnerability; in the meantime, implement VPN session limits and monitor for abnormal memory usage patterns on affected devices.

Recommended fix High confidence

ASA: 9.16.4.85, 9.18.4.66, 9.20.4, or 9.22.2.4 (depending on starting branch) | FTD: 7.0.9, 7.2.11, 7.4.3, or 7.6.4 (depending on starting branch)

  1. 1. Identify the currently running ASA or FTD software version using 'show version' command
  2. 2. Determine the appropriate upgrade path based on current version from the affected version ranges
  3. 3. Download the fixed software version from Cisco (refer to sec.cloudapps.cisco.com for official downloads)
  4. 4. Back up the current device configuration
  5. 5. Upload the new software image to the device
  6. 6. Schedule a maintenance window as the device will reload during upgrade
  7. 7. Initiate the upgrade using 'install piper' command on ASA or appropriate method for FTD
  8. 8. Verify successful installation with 'show version' confirming the fixed version is running
Caveat Standard Cisco upgrade risks apply - device reload required; ensure compatibility with existing VPN client configurations; test thoroughly in staging before production deployment

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

Fix this in Adaptive Security Appliance Software Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
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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-2026-20105 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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