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Adaptive Security Appliance SoftwareOperating system · Cisco

CVE-2011-0393

HIGH · 7.8 CVSS v2.0 Published 2011-02-25
Fix available
A fix is available. Upgrade to after 8.3 or later.
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 Appliances (ASA) 5500 series devices with software 7.0 before 7.0(8.12), 7.1 and 7.2 before 7.2(5.2), 8.0 before 8.0(5.21), 8.1 before 8.1(2.49), 8.2 before 8.2(3.6), and 8.3 before 8.3(2.7) and Cisco PIX Security Appliances 500 series devices, when transparent firewall mode is configured but IPv6 is not configured, allow remote attackers to cause a denial of service (packet buffer exhaustion and device outage) via IPv6 traffic, aka Bug ID CSCtj04707.

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 denial-of-service vulnerability in Cisco ASA 5500 series and PIX 500 series security appliances allows remote attackers to exhaust packet buffers by sending IPv6 traffic to devices configured in transparent firewall mode without IPv6 configured. The device can crash and become unavailable.

MitigationUpgrade Cisco ASA software to version 7.0(8.12), 7.2(5.2), 8.0(5.21), 8.1(2.49), 8.2(3.6), or 8.3(2.7) or later; alternatively, configure IPv6 properly or disable transparent firewall mode if not needed.

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:<= 8.3\(1\)= 7.0= 7.0\(0\)= 7.0\(2\)= 7.0\(4\)= 7.0\(5\)= 7.0\(5.2\)= 7.0\(6.7\)= 7.0.1= 7.0.1.4= 7.0.2= 7.0.4
5500 Series Adaptive Security ApplianceHardware / appliance
Affected:all versions
Asa 5500Hardware / appliance
Affected:all versions
Pix 500Hardware / appliance
Affected:all versions

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 device model and confirm it is an affected Cisco ASA 5500 or PIX 500 appliance
    Run 'show version' or 'show hardware' command on the device to display the model number and hardware information
    Affected if The device is a Cisco ASA 5500 series or PIX 500 series security appliance
  2. Check the installed ASA software version
    Run 'show version' to display the running software version and compare it against the affected version list (<=8.3(1), 7.0.x, 7.2.x, 7.4.x, 8.0.x, 8.1.x, 8.2.x, 8.3(1))
    Affected if The installed ASA software version is 8.3(1) or earlier, or matches any of the specific 7.0.x versions listed in the affected products
  3. Verify if the device is configured in transparent firewall mode
    Run 'show firewall' or check the configuration with 'show run | include firewall' to determine if the device is operating in transparent mode
    Affected if The device is configured in transparent firewall mode (also called 'transparent' or 'bridge-group' mode)
  4. Check whether IPv6 is configured on the device
    Run 'show ipv6 interface' or 'show run | include ipv6' to determine if IPv6 has been explicitly configured
    Affected if IPv6 is NOT configured on the device (no IPv6 interface assignments or IPv6 configuration is missing)
  5. Determine if the device is exposed to incoming IPv6 traffic
    Review network topology and access lists with 'show access-list' to determine if the device can receive IPv6 packets from external or untrusted networks
    Affected if The device can receive IPv6 traffic from network sources while in transparent mode without IPv6 configured

A user is affected if they have a Cisco ASA 5500 or PIX 500 device running an affected software version, configured in transparent firewall mode, without IPv6 configured, and exposed to IPv6 traffic.

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 a release after 8.3
Interim mitigation

Upgrade Cisco ASA software to version 7.0(8.12), 7.2(5.2), 8.0(5.21), 8.1(2.49), 8.2(3.6), or 8.3(2.7) or later; alternatively, configure IPv6 properly or disable transparent firewall mode if not needed.

Fix this in Adaptive Security Appliance Software Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA3.0 h
21.0 hours of engineering $3,680
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,888.

Scan for this in your stack

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dbcve dependency scanner

Check whether your project pulls in CVE-2011-0393 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

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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-2011-0393 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

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