CVE-2019-1977
CVE-2019-1977 is a medium-severity vulnerability in Cisco Nx-os with a CVSS 3.x base score of 6.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-371.
Key facts
- Severity: Medium (CVSS 3.x base score 6.8)
- CVSS v2: 4.3
- EPSS exploit prediction: 1% (70th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-371
- Affected product: Cisco Nx-os
- Published:
- Last modified:
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.
Frequently asked questions
- What is CVE-2019-1977?
- 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.
- How severe is CVE-2019-1977?
- CVE-2019-1977 has a CVSS 3.x base score of 6.8, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2019-1977 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (70th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2019-1977?
- CVE-2019-1977 primarily affects Cisco Nx-os. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
- How do I fix CVE-2019-1977?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
- When was CVE-2019-1977 published?
- CVE-2019-1977 was published on 2019-08-30 and last updated on 2026-06-17.
References
Affected products (4)
- cpe:2.3:o:cisco:nx-os:12.3\(1h\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:nx-os:13.1\(2m\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:nx-os:13.1\(2o\):*:*:*:*:*:*:*
- cpe:2.3:o:cisco:nx-os:13.1\(2p\):*:*:*:*:*:*:*
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