Ios XrOperating system · Cisco
CVE-2017-6731
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 · uneditedA vulnerability in Multicast Source Discovery Protocol (MSDP) ingress packet processing for Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause the MSDP session to be unexpectedly reset, causing a short denial of service (DoS) condition. The MSDP session will restart within a few seconds. More Information: CSCvd94828. Known Affected Releases: 4.3.2.MCAST 6.0.2.BASE. Known Fixed Releases: 6.3.1.19i.MCAST 6.2.3.1i.MCAST 6.2.2.17i.MCAST 6.1.4.12i.MCAST.
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 confidenceA vulnerability in the Multicast Source Discovery Protocol (MSDP) ingress packet processing of Cisco IOS XR Software allows an unauthenticated remote attacker to cause the MSDP session to reset, resulting in a brief denial of service. The attacker sends specially crafted MSDP packets that trigger the unexpected session reset.
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
Ios XrOperating system
= 4.3.2.mcast= 6.0.2.baseCVSS 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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Identify the Cisco IOS XR software versionRun the command 'show version' on the router and locate the IOS XR version string in the outputAffected if The displayed version matches 4.3.2.mcast or 6.0.2.base, or falls within the affected version range between these releases
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Confirm the system is running Cisco IOS XRRun 'show version' and verify the operating system name in the output contains 'IOS XR'Affected if The system is not running Cisco IOS XR (the vulnerability only affects this specific platform)
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Determine if MSDP is enabledRun 'show msdp peer' or 'show running-config | include msdp' to check for active MSDP configurationAffected if MSDP is not configured or enabled - the vulnerability requires MSDP to be active to be exploitable
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Check for MSDP peer relationshipsRun 'show msdp peer' to list configured MSDP peersAffected if MSDP peers are configured and active - the vulnerability triggers when processing incoming MSDP packets from these peers or other sources
You are affected if you are running Cisco IOS XR versions 4.3.2.mcast or 6.0.2.base (or versions between them) AND have MSDP protocol enabled and configured in your environment.
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 the fixed software releases (6.3.1.19i.MCAST, 6.2.3.1i.MCAST, 6.2.2.17i.MCAST, or 6.1.4.12i.MCAST) from Cisco. If immediate patching is not possible, consider filtering MSDP traffic from untrusted sources at network boundaries to reduce attack surface.
Fix this in Ios Xr
Scoped from the published advisory
- Consultation4.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-6731 — 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-2017-6731 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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