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Secure Firewall Threat DefenseApplication · Cisco

CVE-2020-3179

HIGH · 7.5 CVSS v3.1 Published 2020-05-06
Fix available
A fix is available. Upgrade to 6.3.0.5 / 6.4.0.6 or later.
See remediation →
84/100
Remediation priority · High
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 generic routing encapsulation (GRE) tunnel decapsulation feature of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to a memory handling error when GRE over IPv6 traffic is processed. An attacker could exploit this vulnerability by sending crafted GRE over IPv6 packets with either IPv4 or IPv6 payload through an affected device. A successful exploit could allow the attacker to cause the device to crash, 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 handling error in Cisco FTD's GRE tunnel decapsulation feature allows unauthenticated remote attackers to crash devices by sending crafted GRE over IPv6 packets with IPv4 or IPv6 payloads. The vulnerability exists specifically in how the device processes GRE over IPv6 traffic, leading to a denial of service condition.

MitigationApply the relevant Cisco FTD software patch or upgrade to a fixed version as specified in Cisco's advisory for CVE-2020-3179.

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:>= 6.3.0, < 6.3.0.5>= 6.4.0, < 6.4.0.6
Asa 5505 FirmwareOperating system
Affected:= 9.9\(2\)= 101.5\(1.26\)
Asa 5510 FirmwareOperating system
Affected:= 9.9\(2\)= 101.5\(1.26\)
Asa 5512 X FirmwareOperating system
Affected:= 9.9\(2\)= 101.5\(1.26\)
Asa 5515 X FirmwareOperating system
Affected:= 9.9\(2\)= 101.5\(1.26\)
Asa 5520 FirmwareOperating system
Affected:= 9.9\(2\)= 101.5\(1.26\)
Asa 5525 X FirmwareOperating system
Affected:= 9.9\(2\)= 101.5\(1.26\)
Asa 5540 FirmwareOperating system
Affected:= 9.9\(2\)= 101.5\(1.26\)

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
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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. Identify the Cisco product and software version
    Run 'show version' on the device CLI or check the management interface to confirm whether the device runs Cisco Firepower Threat Defense (FTD) or Cisco ASA, and record the exact version number (for example, 6.3.0.3 or 9.9(2)).
    Affected if The device runs Cisco FTD version 6.3.0 through 6.3.0.4, or 6.4.0 through 6.4.0.5, or ASA firmware version 9.9(2) or 101.5(1.26) on the listed ASA models (5505, 5510, 5512X, 5515X, 5520, 5525X, 5540).
  2. Confirm GRE tunnel decapsulation is configured
    Run 'show run gre' or examine the startup/running configuration for GRE tunnel interface definitions. Look for tunnel source and destination settings that indicate GRE is in use.
    Affected if The device has any GRE tunnel interfaces configured for decapsulation.
  3. Verify IPv6 is enabled on the tunnel transport
    Check the GRE tunnel configuration or the underlying physical/logical interfaces for IPv6 addressing or 'tunnel mode gre ipv6' configuration. Use 'show interface' or review the tunnel interface settings.
    Affected if GRE tunnels are operating over IPv6 transport (IPv6 is configured on the tunnel or the underlying interface that carries the GRE traffic).

The device is affected if it runs a vulnerable FTD or ASA version AND has GRE tunnel decapsulation enabled with IPv6 transport, allowing crafted GRE over IPv6 packets to reach the device.

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
Upgrade available Upgrade to 6.3.0.5 / 6.4.0.6 or later
Fixed in 6.3.0.56.4.0.6
Interim mitigation

Apply the relevant Cisco FTD software patch or upgrade to a fixed version as specified in Cisco's advisory for CVE-2020-3179.

Fix this in Secure Firewall Threat Defense Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing4.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,900
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,040.

Scan for this in your stack

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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-2020-3179 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