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-2020-3569HighActively exploited
Multiple vulnerabilities in the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to immediately crash the IGMP process or cause memory exhaustion and eventual crash. This is due to incorrect handling of IGMP packets.
- CVE-2020-3566HighActively exploited
A vulnerability in the Distance Vector Multicast Routing Protocol (DVMRP) feature of Cisco IOS XR Software could allow an unauthenticated, remote attacker to exhaust process memory of an affected device. This is due to insufficient queue management for IGMP packets.
- CVE-2026-20280High
A vulnerability in Cisco IOS XR Software was discovered during an internal security review. It relates to improper checking or handling of exceptional conditions, classified as CWE-703.
- CVE-2026-20278High
A vulnerability in Cisco IOS XR Software was discovered during an internal security review. It relates to improper neutralization issues, classified as CWE-707.
- CVE-2026-20277High
A vulnerability in Cisco IOS XR Software was discovered during an internal security review. It relates to protection mechanism failure issues, classified as CWE-693.
- CVE-2026-20276High
A vulnerability in Cisco IOS XR Software was discovered during an internal security review. It relates to insufficient control flow management issues, classified as CWE-691.
- CVE-2026-20275High
A vulnerability in Cisco IOS XR Software was discovered during an internal security review. It relates to incorrect calculation issues, classified as CWE-682.
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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS