iOSOperating system · Cisco
CVE-2012-1324
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 · uneditedRace condition in the Zone-Based Firewall in Cisco IOS 15.1 and 15.2, when IPS policies are configured, allows remote attackers to cause a denial of service (device crash) by sending IPv6 packets, aka Bug ID CSCtk53534.
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 confidenceA race condition vulnerability exists in the Zone-Based Firewall feature of Cisco IOS versions 15.1 and 15.2 when Intrusion Prevention System (IPS) policies are configured. The flaw can be triggered by sending specially crafted IPv6 packets to an affected device, causing the device to crash due to the race condition in the firewall's packet processing logic.
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
iOSOperating system
= 15.1= 15.2CVSS 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
- M
- Authentication
- None
- Confidentiality
- None
- Integrity
- None
- Availability
- Complete
AV:N/AC:M/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 checksWork through these to decide whether this CVE applies to you.
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Identify Cisco IOS versionExecute 'show version' command on the device and locate the IOS release line (e.g., 'Cisco IOS Software, Version 15.2(4)E' or similar)Affected if The version begins with 15.1 or 15.2 (exact versions like 15.1, 15.1T, 15.2, 15.2T, etc.)
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Verify Zone-Based Firewall is activeExecute 'show zone-pair' to list configured zone-pairs. If any zone-pairs appear in the output, ZBFW is enabled.Affected if Zone-based firewall is configured and active with zone-pairs present in the output
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Confirm IPS policies are attachedExecute 'show zone-pair security' or inspect the zone-pair output for 'ips' or 'ips-inline' policy actionsAffected if IPS policies (ips or ips-inline) are attached to any zone-pair
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Check IPv6 inspection configurationExecute 'show policy-map type inspect zone-pair' for each zone-pair and look for 'inspect ipv6' or 'ipv6' in the policy configurationAffected if IPv6 inspection is enabled within the Zone-Based Firewall policy
You are affected if your device runs Cisco IOS 15.1 or 15.2, has Zone-Based Firewall configured with IPS policies attached, and has IPv6 inspection enabled on the zone-pairs.
Generated from the published advisory. Verify against your own configuration.
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 dataApply the appropriate Cisco IOS software update or upgrade to a fixed version. As a temporary workaround, consider disabling IPv6 traffic inspection or IPS policies on zone-based firewall configurations if operationally feasible until the patch can be deployed.
Fix this in iOS
Scoped from the published advisory
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,600.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2012-1324 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2012-1324 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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