CVE-2026-20040
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk7th percentile - higher than 7% of all known CVEs
Summary
A vulnerability in the CLI of Cisco IOS XR Software allows an authenticated local attacker to execute arbitrary commands as root on the underlying operating system. This is due to insufficient validation of user arguments passed to specific CLI commands.
Risk Assessment
An attacker with low privileges can escalate to root and gain full control over the device's operating system, compromising confidentiality, integrity, and availability.
Recommendation
Apply security updates provided by Cisco for IOS XR Software immediately and restrict CLI access to trusted users only.
Other vulnerabilities in Cisco IOS XR Software
See all- CVE-2017-6731High
A vulnerability in Multicast Source Discovery Protocol (MSDP) ingress packet processing for Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause the MSDP session to be unexpectedly reset, leading to a short denial of service (DoS) condition. The MSDP session will restart within a few seconds.
- CVE-2017-6728High
A vulnerability in the CLI of Cisco IOS XR Software could allow an authenticated, local attacker to execute arbitrary code at the root privilege level on an affected system, due to Incorrect Permissions.
- CVE-2016-9205High
A vulnerability in the HTTP 2.0 request handling code of Cisco IOS XR Software could allow an unauthenticated, remote attacker to cause the Event Management Service daemon (emsd) to crash, resulting in a denial of service (DoS) condition.
- CVE-2026-20074High
A vulnerability in the IS-IS multi-instance routing feature of Cisco IOS XR Software allows an unauthenticated, adjacent attacker to cause an unexpected restart of the IS-IS process. The issue is due to insufficient input validation of incoming IS-IS packets.
- CVE-2026-20046High
A vulnerability in Cisco IOS XR Software allows a local attacker with low privileges to elevate privileges to full administrative control over the device. The issue stems from incorrect mapping of a CLI command to task groups in the source code.
Original NVD description (English source)
A vulnerability in the CLI of Cisco IOS XR Software could allow an authenticated, local attacker to execute arbitrary commands as root on the underlying operating system of an affected device. This vulnerability is due to insufficient validation of user arguments that are passed to specific CLI commands. An attacker with a low-privileged account could exploit this vulnerability by using crafted commands at the prompt. A successful exploit could allow the attacker to elevate privileges to root and execute arbitrary commands on the underlying operating system.