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Ios XrOperating system · Cisco

CVE-2019-1846

HIGH · 7.4 CVSS v3.0 Published 2019-05-16
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
79/100
Remediation priority · High
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 Multiprotocol Label Switching (MPLS) Operations, Administration, and Maintenance (OAM) implementation of Cisco IOS XR Software for Cisco ASR 9000 Series Aggregation Services Routers could allow an unauthenticated, adjacent attacker to trigger a denial of service (DoS) condition on an affected device. The vulnerability is due to the incorrect handling of certain MPLS OAM packets. An attacker could exploit this vulnerability by sending malicious MPLS OAM packets to an affected device. A successful exploit could allow the attacker to cause the lspv_server process to crash. The crash could lead to system instability and the inability to process or forward traffic though the device, resulting in a DoS condition that require manual intervention to restore normal operating conditions.

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 confidence

A vulnerability in the MPLS Operations, Administration, and Maintenance (OAM) implementation in Cisco IOS XR Software for ASR 9000 routers allows an adjacent, unauthenticated attacker to send malicious MPLS OAM packets that crash the lspv_server process, causing system instability and DoS requiring manual intervention.

MitigationApply the Cisco software update/patch for CVE-2019-1846 when available. Prior to patching, consider network segmentation to restrict adjacent attacker access to affected interfaces.

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:= 5.3.3

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
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Scope
Changed
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.0/AV:A/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 Cisco IOS XR version
    Run 'show version' or 'admin show version' on the router CLI to retrieve the installed IOS XR software version
    Affected if The installed version is exactly 5.3.3
  2. Confirm ASR 9000 platform
    Run 'show inventory' or check the hardware platform designation in 'show version' output to verify the device is an ASR 9000 series router
    Affected if The hardware platform is an ASR 9000 router
  3. Check if MPLS OAM is configured
    Run 'show running-config | include mpls oam' or 'show mpls oam' to see if MPLS OAM functionality is enabled on any interface
    Affected if MPLS OAM is enabled and configured on any interface
  4. Verify lspv_server process status
    Run 'show process lspv_server' or check process health via 'show processes lspv_server location all' to confirm the process is running
    Affected if The lspv_server process is active and handling MPLS OAM operations
  5. Assess network adjacency exposure
    Review interface configurations and network topology to determine if adjacent, unauthenticated attackers can reach MPLS OAM-enabled interfaces
    Affected if MPLS-enabled interfaces are accessible to untrusted adjacent attackers

You are affected if you run IOS XR version 5.3.3 on an ASR 9000 with MPLS OAM enabled on interfaces accessible to adjacent attackers.

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 software update/patch for CVE-2019-1846 when available. Prior to patching, consider network segmentation to restrict adjacent attacker access to affected interfaces.

Fix this in Ios Xr Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,840
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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-2019-1846 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