Ios XrOperating system · Cisco
CVE-2019-16023
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 · uneditedMultiple vulnerabilities in the implementation of Border Gateway Protocol (BGP) Ethernet VPN (EVPN) functionality in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerabilities are due to incorrect processing of BGP update messages that contain crafted EVPN attributes. An attacker could exploit these vulnerabilities by sending BGP EVPN update messages with malformed attributes to be processed by an affected system. A successful exploit could allow the attacker to cause the BGP process to restart unexpectedly, resulting in a DoS condition. The Cisco implementation of BGP accepts incoming BGP traffic only from explicitly defined peers. To exploit these vulnerabilities, the malicious BGP update message would need to come from a configured, valid BGP peer, or would need to be injected by the attacker into the victim's BGP network on an existing, valid TCP connection to a BGP peer.
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 Cisco IOS XR's BGP EVPN implementation allows malformed EVPN attributes in BGP update messages to crash the BGP process, causing denial of service. The attacker must send the malicious BGP update from a configured, valid BGP peer or inject it into an existing TCP connection to a BGP peer.
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
= 6.6.1= 6.6.2= 6.6.25= 7.0.1CVSS 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
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.1/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 versionRun 'show version' or 'admin show version' to display the installed IOS XR versionAffected if The version listed is 6.6.1, 6.6.2, 6.6.25, or 7.0.1 exactly
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Verify BGP is runningRun 'show bgp process' or check that BGP processes are active on the systemAffected if BGP process is running on the device
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Confirm EVPN address family is enabled under BGPRun 'show bgp vrf all evpn' or 'show bgp evpn' to check if EVPN address family is configured under BGPAffected if EVPN address family is configured and active under BGP
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Check for configured BGP peersRun 'show bgp neighbor' or 'show bgp vrf all neighbors' to list configured BGP peersAffected if There are configured BGP peers that can send BGP updates to this device
You are affected if you are running exactly IOS XR version 6.6.1, 6.6.2, 6.6.25, or 7.0.1 AND have BGP running with EVPN enabled and have configured BGP 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 the Cisco IOS XR security update when available, and implement BGP MD5 authentication and route filtering to prevent unauthorized BGP peers from sending crafted updates.
Fix this in Ios Xr
Scoped from the published advisory
- Consultation8.0 h
- Implementation16.0 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 $10,240.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-16023 — 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-2019-16023 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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- Version or environment caveats, and links to real fixes
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