dbcve.org
Ios XeOperating system · Cisco

CVE-2012-4623

HIGH · 7.8 CVSS v2.0 Published 2012-09-27
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
The DHCPv6 server in Cisco IOS 12.2 through 12.4 and 15.0 through 15.2 and IOS XE 2.1.x through 2.6.x, 3.1.xS before 3.1.4S, 3.1.xSG and 3.2.xSG before 3.2.5SG, 3.2.xS, 3.2.xXO, 3.3.xS, and 3.3.xSG before 3.3.1SG allows remote attackers to cause a denial of service (device reload) via a malformed DHCPv6 packet, aka Bug ID CSCto57723.

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 DHCPv6 server in Cisco IOS 12.2-12.4 and 15.0-15.2, and IOS XE multiple versions contains a vulnerability where processing a malformed DHCPv6 packet causes the device to reload, resulting in denial of service.

MitigationApply the appropriate Cisco IOS/IOS XE software update from the advisory. If patching is delayed, restrict DHCPv6 traffic at network boundaries or disable the DHCPv6 server if not required.

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
Ios XeOperating system
Affected:= 2.1= 2.1.0= 2.1.1= 2.1.2= 2.2= 2.2.1= 2.2.2= 2.2.3= 2.3= 2.3.0= 2.3.1= 2.3.1t
iOSOperating system
Affected:= 12.3= 12.3\(1a\)= 12.3\(2\)ja= 12.3\(2\)ja5= 12.3\(2\)jk= 12.3\(2\)jk1= 12.3\(2\)t3= 12.3\(2\)t8= 12.3\(2\)xa4= 12.3\(2\)xa5= 12.3\(2\)xc1= 12.3\(2\)xc2

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 the Cisco IOS/IOS XE version
    Execute 'show version' on the device CLI and locate the version string in the output
    Affected if The version string matches any of the affected versions listed in the advisory (IOS 12.2-12.4, 15.0-15.2, or IOS XE 2.1.x through 2.3.1t)
  2. Verify IPv6 is enabled on the device
    Run 'show ipv6 interface brief' or 'show running-config | include ipv6'
    Affected if IPv6 interfaces are active or IPv6 configuration is present in the running config
  3. Confirm DHCPv6 server is configured
    Run 'show running-config | include ipv6 dhcp pool' or 'show ipv6 dhcp pool' to list DHCPv6 address pools
    Affected if One or more DHCPv6 pools are configured, indicating the DHCPv6 server feature is enabled
  4. Check for DHCPv6 server bindings
    Run 'show ipv6 dhcp binding' to display active DHCPv6 client assignments
    Affected if Bindings exist, confirming the DHCPv6 server is actively assigning addresses to clients
  5. Review DHCPv6 server interface bindings
    Run 'show running-config | section interface' and look for 'ipv6 dhcp server' statements under interface configurations
    Affected if Interfaces are configured with 'ipv6 dhcp server' command, exposing the service on those interfaces

The device is affected if it runs an affected Cisco IOS or IOS XE version AND has the DHCPv6 server feature enabled with active configuration, as the vulnerability triggers when malformed DHCPv6 packets are processed.

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 appropriate Cisco IOS/IOS XE software update from the advisory. If patching is delayed, restrict DHCPv6 traffic at network boundaries or disable the DHCPv6 server if not required.

Fix this in Ios Xe Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing2.0 h
  • Review / QA1.0 h
12.0 hours of engineering $2,160
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,456.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2012-4623 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

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-2012-4623 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