Ubuntu LinuxOperating system · Canonical
CVE-2018-5381
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 Quagga BGP daemon (bgpd) prior to version 1.2.3 has a bug in its parsing of "Capabilities" in BGP OPEN messages, in the bgp_packet.c:bgp_capability_msg_parse function. The parser can enter an infinite loop on invalid capabilities if a Multi-Protocol capability does not have a recognized AFI/SAFI, causing a denial of service.
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 Quagga BGP daemon (bgpd) versions prior to 1.2.3 contain a vulnerability in the bgp_capability_msg_parse function in bgp_packet.c. When parsing BGP OPEN message capabilities, the parser enters an infinite loop when encountering invalid Multi-Protocol capabilities with unrecognized AFI/SAFI values, causing CPU exhaustion and 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
Ubuntu LinuxOperating system
= 14.04= 16.04= 17.10
Debian LinuxOperating system
= 7.0= 8.0= 9.0<= 1.2.2< 2.13.0CVSS 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 Quagga bgpd is installedRun `dpkg -l | grep -i quagga` (Debian/Ubuntu) or `rpm -qa | grep -i quagga` (RHEL-based) to list installed Quagga packagesAffected if The package quagga or quagga-bgpd appears in the output
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Determine installed Quagga versionRun `bgpd -v` or `vtysh -v` to display the bgpd version number, or query the package manager: `dpkg -l quagga` or `rpm -qi quagga`Affected if The reported version is 1.2.2 or earlier, or the version cannot be determined (package may be unpatched)
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Confirm bgpd service is runningRun `ps aux | grep -v grep | grep bgpd` or `systemctl status bgpd` to check if the BGP daemon process is activeAffected if bgpd process is running - the vulnerability is only exploitable when the daemon is active and processing BGP messages
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Verify BGP neighbor configurationExamine the Quagga BGP configuration file (typically /etc/quagga/bgpd.conf or /etc/quagga/bgpd.conf) or run `vtysh -c "show running"` and look for 'neighbor' statements under the BGP router blockAffected if The configuration contains active BGP neighbors - the daemon must be accepting BGP OPEN messages with capabilities for the infinite loop to trigger
You are affected if Quagga bgpd version 1.2.2 or earlier is installed and the bgpd service is running with active BGP neighbor configurations that accept incoming BGP connections.
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 data2.13.0
Upgrade Quagga bgpd to version 1.2.3 or later to receive the patch that adds proper exit conditions for the capability parsing loop when invalid AFI/SAFI values are encountered.
Fix this in Ubuntu Linux
Scoped from the published advisory
- Consultation4.0 h
- Implementation2.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,928.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2018-5381 — 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-2018-5381 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
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