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iOSOperating system · Cisco

CVE-2012-0381

HIGH · 7.5 CVSS v3.1 Published 2012-03-29
Fix available
A fix is available. Upgrade to 3.2.2sg / 3.4.1s or later.
See remediation →
84/100
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
The IKEv1 implementation in Cisco IOS 12.2 through 12.4 and 15.0 through 15.2 and IOS XE 2.1.x through 2.6.x and 3.1.xS through 3.4.xS before 3.4.2S, 3.5.xS before 3.5.1S, and 3.2.xSG before 3.2.2SG allows remote attackers to cause a denial of service (device reload) by sending IKE UDP packets over (1) IPv4 or (2) IPv6, aka Bug ID CSCts38429.

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

The IKEv1 implementation in Cisco IOS 12.2-12.4 and 15.0-15.2, and IOS XE versions 2.1.x-2.6.x, 3.1.xS-3.4.xS, 3.5.xS, and 3.2.xSG contains a flaw that allows remote unauthenticated attackers to cause device reload (denial of service) by sending specially crafted IKE UDP packets over IPv4 or IPv6.

MitigationApply Cisco patches (3.4.2S, 3.5.1S, 3.2.2SG or later) or upgrade to a fixed IOS/IOS XE version. Additionally, implement IKE ACLs or firewall rules to restrict IKE UDP port 500 traffic to trusted peer IP addresses only.

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
Affected:= 12.0= 12.2= 12.2\(1\)= 12.2\(1\)dx= 12.2\(1\)s= 12.2\(1\)t= 12.2\(1\)xa= 12.2\(1\)xd= 12.2\(1\)xd1= 12.2\(1\)xd3= 12.2\(1\)xd4= 12.2\(1\)xe
Ios XeOperating system
Affected:>= 2.1.0, <= 2.6.2>= 3.1.0s, < 3.4.1s>= 3.1.0sg, < 3.2.2sg

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
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/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. Determine the Cisco IOS or IOS XE version
    Execute 'show version' on the device CLI and locate the version string in the output (for IOS XE, the version will contain 'XE' in the designation)
    Affected if The displayed version falls within these ranges: IOS 12.2 through 12.4, IOS 15.0 through 15.2, IOS XE 2.1.0 through 2.6.2, IOS XE 3.1.0S through 3.4.1S, any 3.5.xS version, or IOS XE 3.1.0SG through 3.2.1SG. Compare your exact version number to these ranges.
  2. Verify if IKEv1 is configured on the device
    Execute 'show running-config | include isakmp' or 'show crypto isakmp sa' to check for active IKE security associations and ISAKMP (IKE) policy configuration
    Affected if Any IKEv1 (ISAKMP) policies, profiles, or active security associations are present in the configuration or output. The vulnerability requires IKE to be enabled for the exploit to trigger.
  3. Confirm IKE UDP port 500 is accessible
    Review the device configuration for any 'crypto isakmp' commands or interface ACLs permitting UDP port 500 traffic, and verify network accessibility of UDP port 500 on the device
    Affected if UDP port 500 is open to untrusted networks or the device has IKE configured without restrictive ACLs limiting IKE traffic to known peer IP addresses only.

The device is affected if it runs a Cisco IOS or IOS XE version within the listed vulnerable ranges AND has IKEv1 enabled with UDP port 500 accessible to untrusted networks.

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 3.2.2sg / 3.4.1s or later
Fixed in 3.2.2sg3.4.1s
Interim mitigation

Apply Cisco patches (3.4.2S, 3.5.1S, 3.2.2SG or later) or upgrade to a fixed IOS/IOS XE version. Additionally, implement IKE ACLs or firewall rules to restrict IKE UDP port 500 traffic to trusted peer IP addresses only.

Fix this in iOS Scoped from the published advisory
  • Consultation3.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,800
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,880.

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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-2012-0381 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