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Adaptive Security Appliance SoftwareOperating system · Cisco

CVE-2015-6326

HIGH · 7.8 CVSS v2.0 Published 2015-10-25
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
87/100
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
Cisco Adaptive Security Appliance (ASA) software 7.2 and 8.2 before 8.2(5.58), 8.3 and 8.4 before 8.4(7.29), 8.5 through 8.7 before 8.7(1.17), 9.0 before 9.0(4.37), 9.1 before 9.1(6.6), 9.2 before 9.2(4), 9.3 before 9.3(3.5), and 9.4 before 9.4(1.5) allows remote attackers to cause a denial of service (device reload) via a crafted DNS response, aka Bug ID CSCuu07799.

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

Cisco ASA contains a denial-of-service vulnerability in its DNS inspection functionality. Remote attackers can cause affected devices to reload by sending specially crafted DNS responses that trigger improper handling in the DNS inspection module. The vulnerability affects software versions 7.2 through 9.4 across multiple branches, each requiring specific patch levels.

MitigationUpgrade Cisco ASA software to the fixed versions (8.2(5.58), 8.4(7.29), 8.7(1.17), 9.0(4.37), 9.1(6.6), 9.2(4), 9.3(3.5), or 9.4(1.5) depending on current deployed version. As an interim control, filter or validate DNS responses at upstream network devices.

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:= 7.2.1= 7.2.1.9= 7.2.1.13= 7.2.1.19= 7.2.1.24= 7.2.2= 7.2.2.6= 7.2.2.10= 7.2.2.14= 7.2.2.18= 7.2.2.19= 7.2.2.22

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
Authentication
None
Confidentiality
None
Integrity
None
Availability
Complete

AV:N/AC:L/Au:N/C:N/I:N/A:C

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 device and version
    Log into the ASA CLI and run 'show version' to obtain the installed software version number. Alternatively, use ASDM or Cisco Prime to retrieve the ASA software version from the device inventory.
    Affected if The displayed version matches any of the following: 7.2.1, 7.2.1.9, 7.2.1.13, 7.2.1.19, 7.2.1.24, 7.2.2, 7.2.2.6, 7.2.2.10, 7.2.2.14, 7.2.2.18, 7.2.2.19, 7.2.2.22, or any 7.x, 8.x, 9.0.x, 9.1.x, 9.2.x, 9.3.x, or 9.4.x version that has not been patched to the fixed release levels.
  2. Verify DNS inspection is enabled
    Run 'show service-policy' in the ASA CLI to list all active service policies. Look for entries containing 'inspect dns' or 'DNS' under the Inspection Policy configuration.
    Affected if DNS inspection (inspect dns) is present in any active service policy, indicating the inspection module is actively processing DNS traffic.
  3. Confirm DNS inspection policy configuration
    Run 'show running-config | include inspect dns' to display any DNS inspection configurations currently applied. Also run 'show running-config policy-map' to view all policy maps and their inspection rules.
    Affected if A policy-map contains an inspect dns rule applied to traffic, meaning the device will parse and inspect DNS response packets.

The device is affected if it runs any unpatched Cisco ASA version from 7.2 through 9.4 AND has DNS inspection (inspect dns) enabled in an active service policy, allowing specially crafted DNS responses to trigger a reload.

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 the fixed versions (8.2(5.58), 8.4(7.29), 8.7(1.17), 9.0(4.37), 9.1(6.6), 9.2(4), 9.3(3.5), or 9.4(1.5) depending on current deployed version. As an interim control, filter or validate DNS responses at upstream network devices.

Fix this in Adaptive Security Appliance Software Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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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-2015-6326 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
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  • Version or environment caveats, and links to real fixes
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