CVE-2021-1370: Cisco IOS XR Software for Cisco 8000 Series Routers and Network Convergence System 540 Series Routers Privilege Escalation Vulnerability

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.4% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-02-04 · updated 2026-06-17
Weakness: CWE-78

Description

A vulnerability in a CLI command of Cisco IOS XR Software for the Cisco 8000 Series Routers and Network Convergence System 540 Series Routers running NCS540L software images could allow an authenticated, local attacker to elevate their privilege to root. To exploit this vulnerability, an attacker would need to have a valid account on an affected device. The vulnerability is due to insufficient validation of command line arguments. An attacker could exploit this vulnerability by authenticating to the device and entering a crafted command at the prompt. A successful exploit could allow an attacker with low-level privileges to escalate their privilege level to root.

Affected products

Cisco IOS XR Software: before 7.0.12; from 7.1.0 before 7.2.1; before 7.2.1 — fixed in 7.0.12, 7.2.1

How to fix

Upgrade to a fixed version: Cisco IOS XR Software 7.0.12, 7.2.1. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2021-1370 or the next vulnerability affects your stack