CVE-2019-1977

Cisco Nexus 9000 Series Fabric Switches ACI Mode Border Leaf Endpoint Learning Vulnerability

MEDIUM

6.8

CVSS Score

Published: August 29, 2019 at 09:50 PM UTC

Updated: June 17, 2026 at 02:29 AM UTC

23 products affected across 1 vendorNx OSNexus 9508Nexus 93120Tx

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Severity

MEDIUM6.8

Exploit prediction

EPSS 1%

SSVC

No known exploit

Description

A vulnerability within the Endpoint Learning feature of Cisco Nexus 9000 Series Switches running in Application Centric Infrastructure (ACI) mode could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an endpoint device in certain circumstances. The vulnerability is due to improper endpoint learning when packets are received on a specific port from outside the ACI fabric and destined to an endpoint located on a border leaf when Disable Remote Endpoint Learning has been enabled. This can result in a Remote (XR) entry being created for the impacted endpoint that will become stale if the endpoint migrates to a different port or leaf switch. This results in traffic not reaching the impacted endpoint until the Remote entry can be relearned by another mechanism.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Nx OS · Cisconpm

95%

v < 12.2(4M)12.3(1h)13.1(2m)13.1(2o)13.1(2p)

Affected range stops below 12.2(4M), so it looks safe — our inference, not a vendor statement

cisco-nexus-9000 (environment) · cisco-nexus-93108tc-ex (environment) · cisco-nexus-93108tc-fx (environment) · cisco-nexus-93120tx (environment) · cisco-nexus-93128tx (environment) · cisco-nexus-93180lc-ex (environment) · cisco-nexus-93180yc-ex (environment) · cisco-nexus-93180yc-fx (environment) · cisco-nexus-9332pq (environment) · cisco-nexus-9336c-fx2 (environment) · cisco-nexus-9336pq (environment) · cisco-nexus-9348gc-fxp (environment) · cisco-nexus-9364c (environment) · cisco-nexus-9372px (environment) · cisco-nexus-9372px-e (environment) · cisco-nexus-9372tx (environment) · cisco-nexus-9372tx-e (environment) · cisco-nexus-9396px (environment) · cisco-nexus-9396tx (environment) · cisco-nexus-9504 (environment) · cisco-nexus-9508 (environment) · cisco-nexus-9516 (environment)

Nexus 9000 · Ciscodevice

80%

All versions

Nexus 93108Tc-Ex · Ciscodevice

80%

All versions

Nexus 93108Tc-Fx · Ciscodevice

80%

All versions

Nexus 93120Tx · Ciscodevice

80%

All versions