CVE-2021-1587
CVE-2021-1587 is a high-severity vulnerability in Cisco Nx-os with a CVSS 3.x base score of 8.6. 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-436.
Key facts
- Severity: High (CVSS 3.x base score 8.6)
- CVSS v2: 4.3
- EPSS exploit prediction: 2% (74th percentile)
- Actively exploited: Not listed in CISA KEV
- Weakness: CWE-436
- Affected product: Cisco Nx-os
- Published:
- Last modified:
Description
A vulnerability in the VXLAN Operation, Administration, and Maintenance (OAM) feature of Cisco NX-OS Software, known as NGOAM, could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper handling of specific packets with a Transparent Interconnection of Lots of Links (TRILL) OAM EtherType. An attacker could exploit this vulnerability by sending crafted packets, including the TRILL OAM EtherType of 0x8902, to a device that is part of a VXLAN Ethernet VPN (EVPN) fabric. A successful exploit could allow the attacker to cause an affected device to experience high CPU usage and consume excessive system resources, which may result in overall control plane instability and cause the affected device to reload. Note: The NGOAM feature is disabled by default.
Frequently asked questions
- What is CVE-2021-1587?
- A vulnerability in the VXLAN Operation, Administration, and Maintenance (OAM) feature of Cisco NX-OS Software, known as NGOAM, could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper handling of specific packets with a Transparent Interconnection of Lots of Links (TRILL) OAM EtherType. An attacker could exploit this vulnerability by sending crafted packets, including the TRILL OAM EtherType of 0x8902, to a device that is part of a VXLAN Ethernet VPN (EVPN) fabric. A successful exploit could allow the attacker to cause an affected device to experience high CPU usage and consume excessive system resources, which may result in overall control plane instability and cause the affected device to reload. Note: The NGOAM feature is disabled by default.
- How severe is CVE-2021-1587?
- CVE-2021-1587 has a CVSS 3.x base score of 8.6, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
- Is CVE-2021-1587 being actively exploited?
- It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 2% (74th percentile), an estimate of the probability of exploitation in the next 30 days.
- What products are affected by CVE-2021-1587?
- CVE-2021-1587 affects Cisco Nx-os. See the affected-products list for the exact vulnerable versions.
- How do I fix CVE-2021-1587?
- Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
- When was CVE-2021-1587 published?
- CVE-2021-1587 was published on 2021-08-25 and last updated on 2026-06-17.
References
Affected products (1)
- cpe:2.3:o:cisco:nx-os:-:*:*:*:*:*:*:*
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