dbcve.org
Asa 5505 FirmwareOperating system · Cisco

CVE-2020-3125

CRITICAL · 9.8 CVSS v3.1 Published 2020-05-06
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
100/100
Remediation priority · Urgent
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 Kerberos authentication feature of Cisco Adaptive Security Appliance (ASA) Software could allow an unauthenticated, remote attacker to impersonate the Kerberos key distribution center (KDC) and bypass authentication on an affected device that is configured to perform Kerberos authentication for VPN or local device access. The vulnerability is due to insufficient identity verification of the KDC when a successful authentication response is received. An attacker could exploit this vulnerability by spoofing the KDC server response to the ASA device. This malicious response would not have been authenticated by the KDC. A successful attack could allow an attacker to bypass Kerberos authentication.

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 vulnerability in Cisco ASA's Kerberos authentication feature allows an unauthenticated remote attacker to spoof the Kerberos Key Distribution Center (KDC) response. The ASA fails to properly verify the KDC's identity when processing authentication responses, enabling the attacker to impersonate the KDC and bypass authentication for VPN or device access.

MitigationApply the Cisco ASA software update addressing CVE-2020-3125. Until patched, consider using alternative authentication methods (RADIUS, LDAP) or implement network controls to restrict exposure of the Kerberos authentication interface.

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
Asa 5505 FirmwareOperating system
Affected:= 9.10\(1.220\)
Asa 5510 FirmwareOperating system
Affected:= 9.10\(1.220\)
Asa 5512 X FirmwareOperating system
Affected:= 9.10\(1.220\)
Asa 5515 X FirmwareOperating system
Affected:= 9.10\(1.220\)
Asa 5520 FirmwareOperating system
Affected:= 9.10\(1.220\)
Asa 5525 X FirmwareOperating system
Affected:= 9.10\(1.220\)
Asa 5540 FirmwareOperating system
Affected:= 9.10\(1.220\)
Asa 5545 X FirmwareOperating system
Affected:= 9.10\(1.220\)

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
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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. Check the ASA firmware version
    Log into the ASA CLI and run the command: show version. Look for the firmware version number in the output.
    Affected if The firmware version displayed is 9.10(1.220)
  2. Verify if Kerberos authentication is configured
    Run the command: show running-config aaa-server. Look for any aaa-server entries that use the KERBEROS authentication protocol.
    Affected if Any aaa-server is configured with the Kerberos authentication type
  3. Identify active Kerberos authentication bindings
    Run the command: show running-config | include kerberos. Review output for active Kerberos authentication bindings used for VPN, tunnel-group, or device access.
    Affected if Kerberos authentication is actively bound to any VPN or device access feature
  4. Confirm Kerberos is used for any access method
    Run the command: show running-config tunnel-group and show running-config group-policy (or examine aaa authentication commands) to see if any authentication lists include the configured Kerberos server.
    Affected if Kerberos authentication is specified as the primary or fallback authentication method for any access path

You are affected by this CVE if your ASA runs firmware version 9.10(1.220) AND Kerberos authentication is enabled and used for any VPN or device access feature.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Cisco ASA software update addressing CVE-2020-3125. Until patched, consider using alternative authentication methods (RADIUS, LDAP) or implement network controls to restrict exposure of the Kerberos authentication interface.

Recommended fix Moderate confidence

Obtain the fixed ASA version from Cisco Security Advisory for CVE-2020-3125 (specific version varies by ASA model - check advisory for your model)

  1. Contact Cisco TAC or visit the Cisco Security Advisory for CVE-2020-3125 at tools.cisco.com to obtain the specific fixed ASA software version for your model
  2. Download the recommended fixed ASA software version from Cisco's software download center
  3. Review Cisco's upgrade guide for ASA appliances to understand the upgrade procedure
  4. Before upgrading, backup the current ASA configuration
  5. Perform the upgrade during a planned maintenance window following Cisco's documented upgrade procedure
  6. After upgrade, verify that Kerberos authentication is functioning correctly and the vulnerability is remediated
Caveat ASA upgrades may introduce configuration changes; review release notes for any breaking changes specific to your deployment

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

Fix this in Asa 5505 Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,690
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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-2020-3125 in production — separate from our analysis above.

No notes yet

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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