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Secure Firewall Threat DefenseApplication · Cisco

CVE-2020-3189

HIGH · 8.6 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 →
95/100
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 VPN System Logging functionality for Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a memory leak that can deplete system memory over time, which can cause unexpected system behaviors or device crashes. The vulnerability is due to the system memory not being properly freed for a VPN System Logging event generated when a VPN session is created or deleted. An attacker could exploit this vulnerability by repeatedly creating or deleting a VPN tunnel connection, which could leak a small amount of system memory for each logging event. A successful exploit could allow the attacker to cause system memory depletion, which can lead to a systemwide denial of service (DoS) condition. The attacker does not have any control of whether VPN System Logging is configured or not on the device, but it is enabled by default.

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

Memory leak vulnerability in Cisco Firepower Threat Defense (FTD) VPN System Logging functionality. When VPN sessions are created or deleted, the system generates logging events but fails to properly free the associated memory. An unauthenticated remote attacker can repeatedly establish and tear down VPN tunnels to leak small amounts of memory per event, eventually depleting system memory and causing denial of service.

MitigationApply the Cisco patch for CVE-2020-3189. As a mitigating control, if the VPN System Logging feature can be disabled without impacting operations, this may reduce the attack surface while awaiting patch deployment.

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
Secure Firewall Threat DefenseApplication
Affected:= 6.2.3.12= 6.2.3.13= 6.2.3.14= 6.2.3.15
Asa 5505 FirmwareOperating system
Affected:= 9.9\(2\)= 9.9\(2.21\)= 9.9\(2.52\)= 9.9\(2.55\)
Asa 5510 FirmwareOperating system
Affected:= 9.9\(2\)= 9.9\(2.21\)= 9.9\(2.52\)= 9.9\(2.55\)
Asa 5512 X FirmwareOperating system
Affected:= 9.9\(2\)= 9.9\(2.21\)= 9.9\(2.52\)= 9.9\(2.55\)
Asa 5515 X FirmwareOperating system
Affected:= 9.9\(2\)= 9.9\(2.21\)= 9.9\(2.52\)= 9.9\(2.55\)
Asa 5520 FirmwareOperating system
Affected:= 9.9\(2\)= 9.9\(2.21\)= 9.9\(2.52\)= 9.9\(2.55\)
Asa 5525 X FirmwareOperating system
Affected:= 9.9\(2\)= 9.9\(2.21\)= 9.9\(2.52\)= 9.9\(2.55\)
Asa 5540 FirmwareOperating system
Affected:= 9.9\(2\)= 9.9\(2.21\)= 9.9\(2.52\)= 9.9\(2.55\)

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
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/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. Check Firepower Threat Defense version
    Log into the FTD CLI and run 'show version' or access Cisco Firepower Management Center to view device version
    Affected if Version matches 6.2.3.12, 6.2.3.13, 6.2.3.14, or 6.2.3.15
  2. Check ASA firmware version
    Log into the ASA and run 'show version' command
    Affected if Firmware version matches 9.9(2), 9.9(2.21), 9.9(2.52), or 9.9(2.55)
  3. Verify VPN System Logging is enabled
    Access device configuration and check logging settings for VPN events. In FTD, examine 'Logging' configuration or run 'show logging' to see if VPN system logging is active
    Affected if VPN System Logging feature is enabled and generating VPN session logs
  4. Monitor memory usage for unusual consumption
    Run 'show memory' or 'show system resource memory' periodically to observe if memory is steadily decreasing or remaining abnormally low
    Affected if Memory shows continuous depletion or abnormally low free memory over time, especially during periods of VPN tunnel activity

Device is affected if it runs an affected FTD or ASA version AND has VPN System Logging enabled, with memory depletion observable during VPN session creation/deletion.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Cisco patch for CVE-2020-3189. As a mitigating control, if the VPN System Logging feature can be disabled without impacting operations, this may reduce the attack surface while awaiting patch deployment.

Fix this in Secure Firewall Threat Defense Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
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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-2020-3189 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