Is CVE-2026-20040 in the CISA KEV catalog?

No. CVE-2026-20040 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2026-20040?

CVE-2026-20040 has a CVSS v3 base score of 8.8 (HIGH).

What is the EPSS score for CVE-2026-20040?

CVE-2026-20040 has an EPSS score of 0.17% (7th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2026-20040?

Upgrade ios xr to 25.2.21 or later.

CVE & CISA-KEV Catalog

CVE-2026-20040

HIGH

8.8

CVSS v3

NVD

Description

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.

CWE-78OS Command Injection

How to fix

Remediation Available

ios xrNVD

Affected:< 25.2.21Fixed in:25.2.21CVE-2026-20040derived from NVD

Affected:>= 25.3.1, < 25.4.2Fixed in:25.4.2CVE-2026-20040derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorLocal

Attack ComplexityLow

Privileges RequiredLow

User InteractionNone

ScopeChanged

Impact

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Exploit Intelligence

0.17%probability of exploitation in 30 days

7thpercentile

Low risk: more likely to be exploited than 7% of all known CVEs.

References

Vendor Advisory1

sec.cloudapps.cisco.com

Related Vulnerabilities

Other CWE-78 (OS Command Injection) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2021-1498	Critical	9.8	100%	KEV	Fix
CVE-2014-6271	Critical	9.8	100%	KEV	Fix
CVE-2019-16920	Critical	9.8	100%	KEV	-
CVE-2022-44877	Critical	9.8	100%	KEV	Fix
CVE-2020-8515	Critical	9.8	100%	KEV	-
CVE-2020-9054	Critical	9.8	100%	KEV	Fix

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-07-01.