CVE-2021-1588: Cisco NX-OS Software MPLS OAM Denial of Service Vulnerability

Severity: high (CVSS 8.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-08-25 · updated 2026-06-17
Weakness: CWE-126

Description

A vulnerability in the MPLS Operation, Administration, and Maintenance (OAM) feature of Cisco NX-OS Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability is due to improper input validation when an affected device is processing an MPLS echo-request or echo-reply packet. An attacker could exploit this vulnerability by sending malicious MPLS echo-request or echo-reply packets to an interface that is enabled for MPLS forwarding on the affected device. A successful exploit could allow the attacker to cause the MPLS OAM process to crash and restart multiple times, causing the affected device to reload and resulting in a DoS condition.

Affected products

Cisco NX-OS: 7.0(3)i7(9), 8.4(1), 9.3(7)

References

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