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Adaptive Security Appliance SoftwareOperating system · Cisco

CVE-2012-4643

HIGH · 7.1 CVSS v2.0 Published 2012-10-29
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
80/100
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 DHCP server on Cisco Adaptive Security Appliances (ASA) 5500 series devices, and the ASA Services Module (ASASM) in Cisco Catalyst 6500 series devices, with software 7.0 before 7.2(5.8), 7.1 before 7.2(5.8), 7.2 before 7.2(5.8), 8.0 before 8.0(5.28), 8.1 before 8.1(2.56), 8.2 before 8.2(5.27), 8.3 before 8.3(2.31), 8.4 before 8.4(3.10), 8.5 before 8.5(1.9), and 8.6 before 8.6(1.5) does not properly allocate memory for DHCP packets, which allows remote attackers to cause a denial of service (device reload) via a series of crafted IPv4 packets, aka Bug ID CSCtw84068.

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 DHCP server implementation in Cisco ASA 5500 series devices and ASA Services Module (ASASM) contains a memory allocation flaw when processing DHCP packets. By sending a series of crafted IPv4 DHCP packets, a remote attacker can trigger improper memory handling, causing the device to reload (denial of service).

MitigationUpdate Cisco ASA software to the fixed versions (7.2(5.8), 8.0(5.28), 8.1(2.56), 8.2(5.27), 8.3(2.31), 8.4(3.10), 8.5(1.9), or 8.6(1.5) or later. If patching is not immediately feasible, consider disabling the DHCP server feature if unused or implementing network access controls to limit DHCP traffic to trusted sources.

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:= 7.0= 7.0\(0\)= 7.0\(1\)= 7.0\(2\)= 7.0\(4\)= 7.0\(5\)= 7.0\(5.2\)= 7.1= 7.1\(2\)= 7.1\(2.5\)= 7.1\(2.27\)= 7.1\(2.48\)
5500 Series Adaptive Security ApplianceHardware / appliance
Affected:all versions
Catalyst 6500Hardware / appliance
Affected:all versions
Catalyst 6503 EHardware / appliance
Affected:all versions
Catalyst 6504 EHardware / appliance
Affected:all versions
Catalyst 6506 EHardware / appliance
Affected:all versions
Catalyst 6509 EHardware / appliance
Affected:all versions
Catalyst 6509 Neb AHardware / 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
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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify device model
    Use 'show version' or 'show inventory' command to confirm the device is a Cisco ASA 5500 Series Adaptive Security Appliance, ASA Services Module, or Cisco Catalyst 6500 series switch
    Affected if Device is not one of these models, the vulnerability does not apply
  2. Check ASA software version
    Execute 'show version' and locate the 'Cisco Adaptive Security Appliance Software' version line. Compare the version number against the affected list: 7.0, 7.0(0), 7.0(1), 7.0(2), 7.0(4), 7.0(5), 7.0(5.2), 7.1, 7.1(2), 7.1(2.5), 7.1(2.27), 7.1(2.48)
    Affected if The installed version matches one of these specific versions or falls within the 'all versions' category for Cisco 5500 Series ASA or Catalyst 6500 models
  3. Verify DHCP server is enabled
    Run 'show run dhcpd' or 'show dhcpd statistics' to determine if the DHCP server feature is configured and active on the device
    Affected if DHCP server is enabled and processing DHCP requests, the device is vulnerable to the memory handling flaw when crafted packets are received

The device is affected if it is a Cisco ASA 5500 series, ASA Services Module, or Catalyst 6500 model running an affected software version with the DHCP server feature enabled.

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

Update Cisco ASA software to the fixed versions (7.2(5.8), 8.0(5.28), 8.1(2.56), 8.2(5.27), 8.3(2.31), 8.4(3.10), 8.5(1.9), or 8.6(1.5) or later. If patching is not immediately feasible, consider disabling the DHCP server feature if unused or implementing network access controls to limit DHCP traffic to trusted sources.

Fix this in Adaptive Security Appliance Software Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,330
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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-2012-4643 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