CVE-2016-10396
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 racoon daemon in IPsec-Tools 0.8.2 contains a remotely exploitable computational-complexity attack when parsing and storing ISAKMP fragments. The implementation permits a remote attacker to exhaust computational resources on the remote endpoint by repeatedly sending ISAKMP fragment packets in a particular order such that the worst-case computational complexity is realized in the algorithm utilized to determine if reassembly of the fragments can take place.
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 · moderate confidenceThe racoon daemon in IPsec-Tools 0.8.2 contains a computational-complexity vulnerability in its ISAKMP fragment parsing and storage logic. Attackers can send ISAKMP fragments in a specific order that triggers worst-case O(n²) or worse complexity in the fragment reassembly validation algorithm, causing CPU exhaustion on the targeted system.
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= 0.8.2CVSS 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:3.0/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 checksWork through these to decide whether this CVE applies to you.
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Verify racoon daemon versionRun 'racoon -V' or check package manager for ipsec-tools version (e.g., 'rpm -q ipsec-tools' or 'dpkg -l ipsec-tools')Affected if Version is exactly 0.8.2
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Confirm racoon is runningCheck running processes with 'ps aux | grep racoon' or 'pgrep racoon'Affected if Racoon daemon is active and processing ISAKMP connections
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Inspect ISAKMP port exposureCheck if UDP ports 500/4500 are open and listening using 'netstat -anp | grep -E "(500|4500)"' or 'ss -anp | grep -E "(500|4500)"'Affected if ISAKMP ports are exposed to untrusted networks and racoon is accepting connections
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Review racoon configuration for fragment handlingExamine /etc/racoon/racoon.conf (or equivalent path) for 'generate_policy' and fragment-related settings; also check /etc/racoon/*.conf include filesAffected if Racoon is configured to process ISAKMP packets from untrusted peers without rate limiting
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Monitor for ISAKMP fragment trafficUse packet capture (e.g., 'tcpdump -i <interface> udp port 500 or udp port 4500') to observe incoming ISAKMP fragment packetsAffected if High volume of fragmented ISAKMP packets from external sources is observed
A system is affected if it runs racoon from IPsec-Tools 0.8.2, has ISAKMP ports (500/4500) exposed to untrusted networks, and is processing ISAKMP fragments from untrusted peers.
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 dataApply available patches for IPsec-Tools; if no patch exists, implement network-level rate limiting on ISAKMP ports (500/4500) and consider firewall rules to limit exposure to untrusted peers.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2016-10396 — 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-2016-10396 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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- 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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