dbcve.org
Pix Firewall 501Hardware / appliance · Cisco

CVE-2006-4194

MEDIUM · 5.0 CVSS v2.0 Published 2006-08-17
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
59/100
Remediation priority · Elevated
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
Unspecified vulnerability in Cisco PIX 500 Series Security Appliances allows remote attackers to send arbitrary UDP packets to intranet devices via unspecified vectors involving Session Initiation Protocol (SIP) fixup commands, a different issue than CVE-2006-4032. NOTE: the vendor, after working with the researcher, has been unable to reproduce the issue

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 · low confidence

Vulnerability in Cisco PIX 500 Series Security Appliances allows remote attackers to send arbitrary UDP packets to intranet devices through unspecified vectors involving Session Initiation Protocol (SIP) fixup commands. The SIP inspection/fixup feature, designed to handle NAT traversal for SIP traffic, appears to have a flaw that could be exploited to bypass the firewall and inject arbitrary UDP packets into the internal network.

MitigationSince Cisco PIX 500 series is end-of-life and no patches were released (Cisco could not reproduce the issue), the recommended remediation is to migrate to a supported platform such as Cisco ASA or other next-generation firewall. If continued PIX operation is required, restrict SIP traffic at network boundaries and disable SIP fixup 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
Pix Firewall 501Hardware / appliance
Affected:all versions
Pix Firewall 506Hardware / appliance
Affected:all versions
Pix Firewall 515Hardware / appliance
Affected:all versions
Pix Firewall 515eHardware / appliance
Affected:all versions
Pix Firewall 520Hardware / appliance
Affected:all versions
Pix Firewall 525Hardware / appliance
Affected:all versions
Pix Firewall 535Hardware / appliance
Affected:all versions
Pix Firewall SoftwareOperating system
Affected:= 6.3

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
Partial
Availability
None

AV:N/AC:L/Au:N/C:N/I:P/A:N

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 PIX model
    Access the PIX CLI and run the 'show version' command to confirm the device model is one of the following: PIX 501, 506, 515, 515e, 520, 525, or 535
    Affected if The device model is any Cisco PIX 500 series model listed in the affected products
  2. Check the PIX software version
    Run 'show version' in the PIX CLI and note the software version number displayed
    Affected if The software version is 6.3 (exact match) or the device is running any version of PIX software on the affected hardware models
  3. Verify if SIP fixup is enabled
    Run 'show configuration' or 'show running-config' and search for 'sip' or 'fixup protocol sip' statements. Also check with 'show fixup protocol sip'
    Affected if SIP fixup/protocol inspection for SIP is explicitly enabled in the configuration
  4. Check for SIP inspection mapping rules
    Examine the configuration for 'inspect sip' commands under policy maps or global inspection rules using 'show running-config'
    Affected if SIP inspection is applied as part of the inspection policy
  5. Review UDP inspection handling
    Check if there are any custom fixup or inspection rules for UDP-based protocols that may interact with SIP traffic using 'show fixup'
    Affected if UDP-related fixup rules exist that handle SIP traffic flow

You are affected if you are running a Cisco PIX 500 series appliance (any model) or PIX Software 6.3, and SIP fixup/inspection is enabled in your configuration.

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

Since Cisco PIX 500 series is end-of-life and no patches were released (Cisco could not reproduce the issue), the recommended remediation is to migrate to a supported platform such as Cisco ASA or other next-generation firewall. If continued PIX operation is required, restrict SIP traffic at network boundaries and disable SIP fixup if not needed.

Fix this in Pix Firewall 501 Scoped from the published advisory
  • Consultation8.0 h
  • Implementation24.0 h
  • Testing8.0 h
  • Review / QA4.0 h
44.0 hours of engineering $7,840
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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-2006-4194 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
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  • No spam, self-promotion, credentials, or personal data