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

published 2019-08-29 7 y ago modified 2026-06-17 4 mo ago also EUVD-2019-10534

cvss: 6.8; version 3.0, CNA
cisa kev: Not listed; not in CISA's catalog
epss: 1.5%; EPSS 1.5% chance of exploitation in 30 days, percentile 74%
public exploits: 0; none known

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.

Patch / fix

fixed in 1

Cisco Cisco Nexus 9000 Series Fabric Switches in ACI 12.2(4M)

CISA SSVC

Exploitation: none
Automatable: no
Technical impact: partial
Assessed: 23 mo ago (2024-11-21)

Exploit prediction

1.49% chance of exploitation in the next 30 days, higher than 74% of all scored CVEs (FIRST EPSS, 2026-11-08).

CVSS scores

assigned by	version	score	vector
CNA	3.0	6.8	CVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:N/I:N/A:H
NVD	3.0	7.5	CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD	2.0	4.3	AV:N/AC:M/Au:N/C:N/I:N/A:P

Affected products

Cisco Cisco Nexus 9000 Series Fabric Switches in ACI

Classification

Weakness

CWE-371 State Issues

References

tools.cisco.com /security/center/content/CiscoSecurityAdvisory/cisco-sa-20190828-nexus-aci-dos
vendor-advisory

Sources

CVE List CVE-2019-1977
NVD CVE-2019-1977

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Summary