Review reviewHigh

CVE-2026-20040

Cisco Cisco IOS XR Software, ios xr

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.

CVSS: 8.8
EPSS: 0.17%
CISA KEV: Not listed
Published: 2026.03.12

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.17%

Technical severityCVSS 8.8

Vulnerability overview

Affected product and versions

Product: Cisco Cisco IOS XR Software, ios xr
Affected versions: 6.5.3, 6.5.29, 6.5.1, 6.6.1, 6.5.2, 6.5.92, 6.5.15, 6.6.2, 7.0.1, 6.6.25, 6.5.26, 6.6.11, 6.5.25, 6.5.28, 6.5.93, 6.6.12, 6.5.90, 7.1.1, 7.0.90, 6.6.3
Fixed versions: 25.2.21, 25.4.2

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that Cisco Cisco IOS XR Software, ios xr and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
CWE: CWE-78