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Adaptive Security Appliance SoftwareOperating system · Cisco

CVE-2022-20737

HIGH · 7.1 CVSS v3.1 Published 2022-05-03
Fix available
A fix is available. Upgrade to 9.12.4.38 / 9.14.4 or later.
See remediation →
77/100
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 handler for HTTP authentication for resources accessed through the Clientless SSL VPN portal of Cisco Adaptive Security Appliance (ASA) Software could allow an authenticated, remote attacker to cause a denial of service (DoS) condition on an affected device or to obtain portions of process memory from an affected device. This vulnerability is due to insufficient bounds checking when parsing specific HTTP authentication messages. An attacker could exploit this vulnerability by sending malicious traffic to an affected device acting as a VPN Gateway. To send this malicious traffic, an attacker would need to control a web server that can be accessed through the Clientless SSL VPN portal. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition, or to retrieve bytes from the device process memory that may contain sensitive information.

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 bounds checking vulnerability in the HTTP authentication handler for Cisco ASA Clientless SSL VPN portal allows an authenticated remote attacker to cause device reload (DoS) or extract sensitive process memory contents. Exploitation requires the attacker to control a web server accessible through the VPN portal and send specially crafted HTTP authentication messages.

MitigationApply the relevant Cisco ASA Software security update. If immediate patching is not possible, restrict VPN portal access to trusted users and monitor for unusual authentication 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:< 9.12.4.38>= 9.13.0, < 9.14.4>= 9.15.0, < 9.15.1.21>= 9.16.0, < 9.16.2.14>= 9.17.0, < 9.17.1.7

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
Unchanged
Confidentiality
Low
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/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 ASA device and obtain software version
    Run 'show version' on the ASA CLI or check via ASDM to retrieve the installed Cisco ASA Software version number
    Affected if The version falls within any of these ranges: < 9.12.4.38, >= 9.13.0 and < 9.14.4, >= 9.15.0 and < 9.15.1.21, >= 9.16.0 and < 9.16.2.14, or >= 9.17.0 and < 9.17.1.7
  2. Confirm Clientless SSL VPN is enabled
    Run 'show running-config webvpn' or check via ASDM under Remote Access VPN > Clientless SSL VPN Access to see if the webvpn/Clientless VPN is configured and enabled
    Affected if Clientless SSL VPN (webvpn) is active on the device
  3. Verify VPN portal authentication configuration
    Check 'show run aaa authentication' and review the webvpn gateway and tunnel group settings to see which authentication methods (RADIUS, TACACS+, local) are in use for VPN portal access
    Affected if The VPN portal accepts remote user authentication, especially from external or untrusted authentication servers
  4. Confirm VPN portal is externally accessible
    Review the interface configuration with 'show running-config interface' and check NAT/external IP mappings to determine if the SSL VPN portal is reachable from outside networks
    Affected if The Clientless SSL VPN portal is exposed to untrusted networks or the internet

You are affected if your ASA runs a version within the affected ranges AND Clientless SSL VPN is enabled and accessible for authentication requests.

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 9.12.4.38 / 9.14.4 / 9.15.1.21 or later
Fixed in 9.12.4.389.14.49.15.1.21
Interim mitigation

Apply the relevant Cisco ASA Software security update. If immediate patching is not possible, restrict VPN portal access to trusted users and monitor for unusual authentication patterns.

Recommended fix High confidence

9.16.2.14 (or latest available 9.16.x release)

  1. 1. Identify the current Cisco ASA software version by running 'show version' in privileged EXEC mode
  2. 2. Determine which version branch your current software falls into (9.12.x, 9.13.x-9.14.x, 9.15.x, or 9.16.x)
  3. 3. For 9.12.x branch: upgrade to version 9.12.4.38 or later
  4. 4. For 9.13.x-9.14.x branch: upgrade to version 9.14.4 or later
  5. 5. For 9.15.x branch: upgrade to version 9.15.1.21 or later
  6. 6. For 9.16.x branch: upgrade to version 9.16.2.14 or later
  7. 7. Download the appropriate Cisco ASA software image from Cisco.com (requires valid service contract)
  8. 8. Upload the new software image to the ASA using 'copy' command or through ASDM
Caveat Review Cisco ASA release notes for any configuration changes or deprecated features between your current version and the target version before upgrading

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-2022-20737 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
  • No spam, self-promotion, credentials, or personal data