Ios XrOperating system · Cisco
CVE-2019-1909
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 the implementation of Border Gateway Protocol (BGP) functionality in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected system. The vulnerability is due to incorrect processing of certain BGP update messages. An attacker could exploit this vulnerability by sending BGP update messages that include a specific set of 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 from explicitly defined peers only. To exploit this vulnerability, 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 · moderate confidenceA vulnerability in Cisco IOS XR Software's BGP implementation allows unauthenticated remote attackers to cause a DoS by sending specially crafted BGP update messages with specific attributes. The attack triggers an unexpected BGP process restart. Exploitation requires the malicious BGP update to originate from a configured, valid BGP peer or be injected into an existing TCP connection to a valid 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
>= 4.3.1, < 6.6.2CVSS 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
- High
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
CVSS:3.0/AV:N/AC:H/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 device operating systemRun 'show version' or check system properties to confirm the device runs Cisco IOS XR SoftwareAffected if The device is not running Cisco IOS XR (this CVE only applies to IOS XR)
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Determine the IOS XR versionRun 'show version' and locate the IOS XR version number in the output. Compare it to the affected range: 4.3.1 through 6.6.1Affected if The installed version is 4.3.1 or higher but lower than 6.6.2
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Verify BGP is enabledRun 'show bgp summary' or 'show bgp process' to check if BGP process is active on the systemAffected if BGP is not running or not configured (the vulnerability requires an active BGP instance)
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Check for configured BGP peersRun 'show bgp neighbors' to list configured BGP peers. The exploit requires a valid, configured BGP peer relationshipAffected if No BGP peers are configured (exploitation requires a valid BGP peer relationship)
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Look for BGP process restartsReview system logs or run 'show log' to search for messages indicating unexpected BGP process restarts or crashesAffected if BGP process has been restarting unexpectedly, which is a symptom of exploitation
The environment is affected only if the device runs Cisco IOS XR version 4.3.1 through 6.6.1 and has BGP enabled with configured peers, making it vulnerable to specially crafted BGP update messages causing process restarts.
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 data6.6.2
Apply the Cisco IOS XR Software patch when available. Additionally, implement BGP peer authentication (MD5), filter BGP peers at network boundaries, and monitor for unexpected BGP process restarts.
Fix this in Ios Xr
Scoped from the published advisory
- Consultation3.0 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 $3,408.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-1909 — 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-2019-1909 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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