dbcve.org
Ios XrOperating system · Cisco

CVE-2019-16019

HIGH · 8.6 CVSS v3.1 Published 2020-09-23
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
95/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
Multiple 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 confidence

The vulnerability exists in Cisco IOS XR Software's BGP EVPN implementation where incorrect processing of BGP update messages containing malformed EVPN attributes can trigger an unexpected restart of the BGP process. An attacker needs to send malicious BGP EVPN messages either from a configured, valid BGP peer or by injecting them into an existing TCP connection to a BGP peer, resulting in denial of service.

MitigationApply the Cisco IOS XR software update addressing CVE-2019-16019. Additionally, implement BGP route validation and peer authentication (MD5, TCP AO) to protect against malicious peer injection, and monitor for anomalous BGP EVPN messages.

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
Affected:= 6.6.1= 6.6.2= 6.6.25= 7.0.1

CVSS 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
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/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 checks

Work through these to decide whether this CVE applies to you.

  1. Determine the Cisco IOS XR software version
    Execute 'show version' on the IOS XR device and locate the version number in the output
    Affected if The installed version is 6.6.1, 6.6.2, 6.6.25, or 7.0.1 exactly matching one of the affected releases
  2. Confirm BGP is running on the device
    Run 'show bgp summary' or 'show processes bgp' to verify the BGP process is active
    Affected if BGP process is running and configured on the device
  3. Verify EVPN address family is enabled under BGP
    Execute 'show bgp l2vpn evpn summary' or examine the BGP configuration for EVPN (L2VPN EVPN) address family entries
    Affected if The EVPN address family is enabled under BGP configuration
  4. Identify configured BGP EVPN peers
    Use 'show bgp l2vpn evpn neighbors' or review BGP configuration for any peer definitions that include EVPN capability
    Affected if There are configured BGP peers with EVPN address family capability
  5. Check for BGP process instability or recent restarts
    Review system logs, use 'show log' or 'show bgp crash-files' to identify any recent BGP process crashes or unexpected restarts
    Affected if BGP process has experienced unexpected restarts or crashes, which may indicate exploitation attempts

The device is affected if it runs Cisco IOS XR version 6.6.1, 6.6.2, 6.6.25, or 7.0.1 with BGP EVPN configured and has active peers capable of sending EVPN update messages.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Cisco IOS XR software update addressing CVE-2019-16019. Additionally, implement BGP route validation and peer authentication (MD5, TCP AO) to protect against malicious peer injection, and monitor for anomalous BGP EVPN messages.

Fix this in Ios Xr Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing6.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,780
Get help mitigating

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,448.

Scan for this in your stack

Free · runs locally
dbcve dependency scanner

Check whether your project pulls in CVE-2019-16019 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.

Get it on GitHub Scan in the browser

References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2019-16019 in production — separate from our analysis above.

No notes yet

Be the first to add a field note for this CVE — a mitigation you’ve verified, a version caveat, or a link to a working fix. Sign in above to contribute.

What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • 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
  • No spam, self-promotion, credentials, or personal data