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Ios XrOperating system · Cisco

CVE-2019-15989

HIGH · 8.6 CVSS v3.1 Published 2020-01-26
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
A vulnerability in the implementation of the Border Gateway Protocol (BGP) functionality in Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition. The vulnerability is due to incorrect processing of a BGP update message that contains a specific BGP attribute. An attacker could exploit this vulnerability by sending BGP update messages that include a specific, malformed attribute 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 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 · high confidence

A parsing vulnerability in Cisco IOS XR Software's BGP implementation allows a remote attacker to send a malformed BGP attribute in an update message, triggering an unexpected restart of the BGP process and causing denial of service. The attacker must have access to a configured, valid BGP peer or inject traffic into an existing BGP TCP session.

MitigationApply the Cisco patch for CVE-2019-15989 to affected IOS XR devices. As a workaround, strictly control BGP peer access and implement BGP MD5 authentication to prevent unauthorized peer connections.

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. Identify the IOS XR version
    Run 'show version' or 'cat /proc/version' if accessible via CLI to determine the installed Cisco IOS XR version
    Affected if The installed version matches 6.6.1, 6.6.2, 6.6.25, or 7.0.1 exactly
  2. Confirm BGP is configured
    Run 'show bgp summary' or 'show ip bgp summary' on the IOS XR device to verify BGP process is running
    Affected if BGP is active and a process exists on the device
  3. List BGP peer configurations
    Run 'show bgp neighbors' or 'show ip bgp neighbors' to display configured BGP peers
    Affected if Any BGP peers are configured, as the vulnerability requires a valid peer or ability to inject into a BGP TCP session
  4. Check BGP neighbor authentication
    Run 'show bgp neighbors' and look for MD5 or TCP MD5 signature configuration under neighbor settings
    Affected if BGP neighbors lack MD5 authentication, increasing exposure to unauthorized peer injection

You are affected if the device runs Cisco IOS XR version 6.6.1, 6.6.2, 6.6.25, or 7.0.1 and has BGP configured with peers, especially without MD5 authentication.

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 patch for CVE-2019-15989 to affected IOS XR devices. As a workaround, strictly control BGP peer access and implement BGP MD5 authentication to prevent unauthorized peer connections.

Fix this in Ios Xr Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
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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-2019-15989 in production — separate from our analysis above.

No notes yet

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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