dbcve.org
Nx OsOperating system · Cisco

CVE-2024-20267

HIGH · 8.6 CVSS v3.1 Published 2024-02-29
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 with the handling of MPLS traffic for Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause the netstack process to unexpectedly restart, which could cause the device to stop processing network traffic or to reload. This vulnerability is due to lack of proper error checking when processing an ingress MPLS frame. An attacker could exploit this vulnerability by sending a crafted IPv6 packet that is encapsulated within an MPLS frame to an MPLS-enabled interface of the targeted device. A successful exploit could allow the attacker to cause a denial of service (DoS) condition. Note: The IPv6 packet can be generated multiple hops away from the targeted device and then encapsulated within MPLS. The DoS condition may occur when the NX-OS device processes the packet.

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 vulnerability in Cisco NX-OS software's MPLS traffic handling allows an unauthenticated remote attacker to cause a denial of service by sending a crafted IPv6 packet encapsulated within an MPLS frame to an MPLS-enabled interface. The root cause is improper error checking when processing ingress MPLS frames, leading to netstack process crashes and potential device reloads.

MitigationApply the Cisco patch for CVE-2024-20267 when available; until then, disable MPLS on vulnerable interfaces or filter MPLS traffic at network boundaries to reduce exposure.

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
Nx OsOperating system
Affected:= 6.0\(2\)a3\(1\)= 6.0\(2\)a3\(2\)= 6.0\(2\)a3\(4\)= 6.0\(2\)a4\(1\)= 6.0\(2\)a4\(2\)= 6.0\(2\)a4\(3\)= 6.0\(2\)a4\(4\)= 6.0\(2\)a4\(5\)= 6.0\(2\)a4\(6\)= 6.0\(2\)a6\(1\)= 6.0\(2\)a6\(1a\)= 6.0\(2\)a6\(2\)

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. Check NX-OS software version
    Execute 'show version' or 'show version | include NXOS' on the device CLI to retrieve the installed NX-OS version string
    Affected if The version displayed matches one of the affected versions: 6.0(2)a3(1), 6.0(2)a3(2), 6.0(2)a3(4), 6.0(2)a4(1), 6.0(2)a4(2), 6.0(2)a4(3), 6.0(2)a4(4), 6.0(2)a4(5), 6.0(2)a4(6), 6.0(2)a6(1), 6.0(2)a6(1a), or 6.0(2)a6(2)
  2. Verify MPLS is enabled on any interface
    Execute 'show mpls interface' or 'show running-config | include mpls' to list interfaces with MPLS functionality activated
    Affected if Any interface shows MPLS as enabled or 'up' in the output, indicating the device can process MPLS-encapsulated traffic
  3. Check for IPv6 configuration on MPLS-enabled interfaces
    Execute 'show ipv6 interface' and cross-reference with the MPLS-enabled interfaces identified in the previous step
    Affected if IPv6 is configured on an interface that also has MPLS enabled, as the attack requires an IPv6 packet encapsulated within an MPLS frame
  4. Confirm MPLS label distribution protocol
    Execute 'show mpls ldp neighbor' or 'show mpls traffic-eng neighbor' to verify LDP or TE neighbors exist, indicating active MPLS label exchange
    Affected if LDP or TE neighbors are established, confirming active MPLS label distribution and potential traffic flow

A device is affected if it runs an affected NX-OS version (6.0(2)a3(1) through 6.0(2)a6(2)) AND has MPLS enabled on at least one interface that also supports IPv6, allowing it to receive the crafted IPv6-in-MPLS packet that triggers the netstack process crash.

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-2024-20267 when available; until then, disable MPLS on vulnerable interfaces or filter MPLS traffic at network boundaries to reduce exposure.

Fix this in Nx Os Scoped from the published advisory
  • Consultation4.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
13.0 hours of engineering $2,330
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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-2024-20267 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