CVE-2006-1646
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 · uneditedThe Internet Key Exchange version 1 (IKEv1) implementation (isakmp_agg.c) in the Shoichi Sakane KAME Project racoon, as used by NetBSD 1.6, 2.x before 20060119, certain FreeBSD releases, and possibly other distributions of BSD or Linux operating systems, when running in aggressive mode, allows remote attackers to cause a denial of service (daemon crash) via crafted IKE packets, as demonstrated by the PROTOS ISAKMP Test Suite for IKEv1.
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 confidenceThe racoon IKE daemon contains a vulnerability in isakmp_agg.c when handling IKEv1 aggressive mode. Remote attackers can send specially crafted IKE packets (as demonstrated by the PROTOS ISAKMP Test Suite) that cause the daemon to crash, resulting in denial of service.
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= 1CVSS 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
- Partial
AV:N/AC:L/Au:N/C:N/I:N/A:P
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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Verify racoon IKE daemon is installedCheck for the presence of the racoon binary or IKE daemon: which racoon, or look in /usr/sbin/racoon, or check package manager listingsAffected if racoon or any IKE daemon based on the ipsec-tools codebase is present on the system
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Determine the IKE daemon versionRun racoon -v, racoon --version, or check the package version via pkg_info (FreeBSD), pkginfo (Solaris), or dpkg/rpm queryAffected if The version is older than the 20060119 update, or cannot be determined (indicating unpatched vintage)
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Confirm IKE service is running and exposedCheck if port 500/UDP (ISAKMP) is listening: netstat -an | grep ':500' or ss -anp | grep 500, and verify the process (ps aux | grep racoon)Affected if The IKE daemon is actively running and bound to a network interface, making it reachable
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Inspect IKE configuration for aggressive modeExamine the racoon configuration file (typically /etc/racoon/racoon.conf or /etc/ipsec.conf) and look for 'aggressive' mode statements in the proposal definitions, or check for remote gateway configurations that use aggressive mode exchangeAffected if Aggressive mode is explicitly enabled or configured in the IKE policy (the vulnerability only triggers when aggressive mode is in use)
The system is affected if a racoon-based IKE daemon version prior to the 20060119 update is running with aggressive mode enabled and is accessible over the network on UDP port 500.
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 dataUpdate racoon/NetBSD/FreeBSD to versions after 20060119, or disable aggressive mode in IKE configuration if not required, and/or filter IKE traffic at network perimeter.
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 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 $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2006-1646 — 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-2006-1646 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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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.
- 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
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