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Adaptive Security Appliance SoftwareOperating system · Cisco

CVE-2017-6609

HIGH · 7.7 CVSS v3.0 Published 2017-04-20
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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 IPsec code of Cisco ASA Software could allow an authenticated, remote attacker to cause a reload of the affected system. The vulnerability is due to improper parsing of malformed IPsec packets. An attacker could exploit this vulnerability by sending malformed IPsec packets to the affected system. Note: Only traffic directed to the affected system can be used to exploit this vulnerability. This vulnerability affects systems configured in routed firewall mode only and in single or multiple context mode. This vulnerability can be triggered by IPv4 and IPv6 traffic. An attacker needs to establish a valid IPsec tunnel before exploiting this vulnerability. This vulnerability affects Cisco ASA Software running on the following products: Cisco ASA 1000V Cloud Firewall, Cisco ASA 5500 Series Adaptive Security Appliances, Cisco ASA 5500-X Series Next-Generation Firewalls, Cisco ASA Services Module for Cisco Catalyst 6500 Series Switches and Cisco 7600 Series Routers, Cisco Adaptive Security Virtual Appliance (ASAv), Cisco Firepower 9300 ASA Security Module, Cisco ISA 3000 Industrial Security Appliance. Fixed versions: 9.1(7.8) 9.2(4.15) 9.4(4) 9.5(3.2) 9.6(2). Cisco Bug IDs: CSCun16158.

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 the IPsec packet parsing code of Cisco ASA Software allows an authenticated remote attacker with an established IPsec tunnel to cause a denial of service via system reload by sending malformed IPsec packets. The issue affects systems in routed firewall mode only, across single or multiple context modes, and can be triggered by both IPv4 and IPv6 traffic.

MitigationUpgrade Cisco ASA Software to one of the fixed versions (9.1(7.8), 9.2(4.15), 9.4(4), 9.5(3.2), or 9.6(2) or later). If immediate patching is not feasible, consider implementing IPsec traffic filtering or tunnel-specific ACLs to restrict malformed packet injection.

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:= 9.0.1= 9.0.2= 9.0.2.10= 9.0.3= 9.0.3.6= 9.0.3.8= 9.0.4= 9.0.4.1= 9.0.4.5= 9.0.4.7= 9.0.4.17= 9.0.4.20

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:3.0/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. Identify Cisco ASA software version
    Execute 'show version' on the ASA CLI and locate the 'Cisco Adaptive Security Appliance Software' line showing the version number
    Affected if The version matches one of the affected releases: 9.0.1, 9.0.2, 9.0.2.10, 9.0.3, 9.0.3.6, 9.0.3.8, 9.0.4, 9.0.4.1, 9.0.4.5, 9.0.4.7, 9.0.4.17, or 9.0.4.20
  2. Confirm the device is in routed firewall mode
    Execute 'show firewall' or 'show running-config | include mode' to verify the firewall mode is set to 'routed'
    Affected if The firewall mode is routed (not transparent mode - the vulnerability only affects routed mode)
  3. Verify IPsec is configured and tunnels exist
    Execute 'show crypto ipsec sa' to display active IPsec security associations
    Affected if There are active IPsec tunnels (the 'current_peer' and 'pkts encaps' fields show non-zero values indicating established tunnels)
  4. Confirm IPsec tunnel is active with an authenticated peer
    Review the output of 'show crypto ipsec sa' for the 'remote identity' field showing the peer IP address and verify proper authentication has occurred
    Affected if The tunnel is established with an authenticated remote peer (an attacker needs an authenticated IPsec tunnel to send malformed packets)

You are affected if your Cisco ASA runs version 9.0.x (specifically the listed versions), operates in routed firewall mode, and has an established IPsec tunnel that could receive malicious packets from an authenticated remote peer.

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

Upgrade Cisco ASA Software to one of the fixed versions (9.1(7.8), 9.2(4.15), 9.4(4), 9.5(3.2), or 9.6(2) or later). If immediate patching is not feasible, consider implementing IPsec traffic filtering or tunnel-specific ACLs to restrict malformed packet injection.

Fix this in Adaptive Security Appliance Software Scoped from the published advisory
  • Consultation2.0 h
  • Implementation2.0 h
  • Testing3.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,390
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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-2017-6609 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