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Adaptive Security Appliance SoftwareOperating system · Cisco

CVE-2017-6607

HIGH · 8.7 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 →
96/100
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 DNS code of Cisco ASA Software could allow an unauthenticated, remote attacker to cause an affected device to reload or corrupt the information present in the device's local DNS cache. The vulnerability is due to a flaw in handling crafted DNS response messages. An attacker could exploit this vulnerability by triggering a DNS request from the Cisco ASA Software and replying with a crafted response. A successful exploit could cause the device to reload, resulting in a denial of service (DoS) condition or corruption of the local DNS cache information. Note: Only traffic directed to the affected device can be used to exploit this vulnerability. This vulnerability affects Cisco ASA Software configured in routed or transparent firewall mode and single or multiple context mode. This vulnerability can be triggered by IPv4 and IPv6 traffic. 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(7.12) 9.2(4.18) 9.4(3.12) 9.5(3.2) 9.6(2.2). Cisco Bug IDs: CSCvb40898.

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 Software's DNS code allows an unauthenticated remote attacker to cause device reload or corrupt the local DNS cache by sending a crafted DNS response to the ASA when it initiates a DNS request. The flaw is in handling specially crafted DNS response messages, and only traffic directed to the affected device can trigger this issue.

MitigationApply the fixed software versions (9.1(7.12), 9.2(4.18), 9.4(3.12), 9.5(3.2), or 9.6(2.2) and later) to address the DNS handling flaw.

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
High
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
High
Availability
High

CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/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. Identify ASA device and version
    Run 'show version' on the Cisco ASA CLI to obtain the software version number
    Affected if The displayed version matches one of the affected versions: 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. Verify DNS service is configured
    Run 'show run dns' to display DNS server configuration, or check 'show running-config | include dns' to see if any DNS settings exist
    Affected if One or more DNS server addresses are configured on the ASA, indicating the device initiates DNS requests
  3. Confirm DNS inspection is enabled
    Run 'show run | include inspect dns' to check if DNS inspection is enabled in the policy map
    Affected if DNS inspection is enabled, which processes DNS responses and could be triggered by crafted packets
  4. Check for DNS proxy configuration
    Run 'show run all dns' and 'show dns' to see if DNS proxy or DNS guard features are configured
    Affected if DNS proxy is enabled, making the ASA vulnerable to malicious DNS response handling

The device is affected if it runs any of the listed affected versions AND has DNS servers configured or DNS inspection/proxy enabled, allowing it to process incoming DNS responses.

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 fixed software versions (9.1(7.12), 9.2(4.18), 9.4(3.12), 9.5(3.2), or 9.6(2.2) and later) to address the DNS handling flaw.

Fix this in Adaptive Security Appliance Software Scoped from the published advisory
  • Consultation8.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,940
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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-2017-6607 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