High Injection

CVE-2026-20040 — Cisco IOS XR Software CLI Privilege Escalation Vulnerability

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.

Published Mar 11, 2026 · Updated Oct 13, 2026 · Sources: NIST National Vulnerability Database, CVE Program (cve.org) e CISA ADP · CNA: cisco

Low

Who exploits it and how urgent it is

A 0–100 score combining confirmed exploitation, ransomware and APT use, public exploits, EPSS and severity.

No exploitation signal in the sources consulted so far.

How the score was calculated

EPSS 0.2% (30-day exploitation probability)+1
Technical severity (high)+6

The score orders the patch queue; it does not replace your asset context (internet exposure, criticality, compensating controls).

Triage

Is it exploited, how likely is exploitation, what does it touch, and how severe do the sources call it.

Exploitation

Not confirmed

Not in CISA KEV — an absence of record, not proof it is unexploited.

EPSS FIRST

0.18%

ahead of 7% of scored CVEs · Oct 14, 2026

Affects

Cisco

Cisco IOS XR Software and 1 more

CVSS base

8.8

High · 2 source(s)

CISA SSVC assessment CISA

Three decision points CISA publishes for the CVEs it assesses (SSVC 2.0.3). A stakeholder decision, not a severity score.

Exploitation

None

none · proof-of-concept · active

Automatable

can an attacker script the kill-chain steps

Technical impact

Total

partial · total control of the vulnerable component

Remediation

Fixes and mitigations documented by the sources — linked to the original advisory.

No fix documented by the sources we poll. That does not mean none exists: check the vendor advisory.

First 24 hours

Ordered from the record’s own fields — exposure first, because you cannot patch what you have not found. A rule-generated starting point.

Identify exposed assets running the affected vendor/product/version combinations (Cisco Cisco IOS XR Software, Cisco Ios Xr).
No fix documented in the sources: reduce exposure and monitor the vendor advisory.
Search available logs for exploit probes matching the vulnerability class (injection), errors and authentication anomalies.

Affected scope

Vendor, product and versions as the sources word them.

Vendor	Product	Versions	Status	Source
Cisco	Cisco IOS XR Software	version 25.3.15version 6.5.3version 6.5.29version 6.5.1version 6.6.1version 6.5.2version 6.5.92version 6.5.15 and 108 more version 6.6.2version 7.0.1version 6.6.25version 6.5.26version 6.6.11version 6.5.25version 6.5.28version 6.5.93version 6.6.12version 6.5.90version 7.1.1version 7.0.90version 6.6.3version 6.7.1version 7.0.2version 7.1.15version 7.2.1version 7.1.2version 6.7.2version 7.0.11version 7.0.12version 7.0.14version 7.1.25version 6.6.4version 7.2.12version 7.3.1version 7.1.3version 6.7.3version 7.4.1version 7.2.2version 6.7.4version 6.5.31version 7.3.15version 7.3.16version 6.8.1version 7.4.15version 6.5.32version 7.3.2version 7.5.1version 7.4.16version 7.3.27version 7.6.1version 7.5.2version 7.8.1version 7.6.15version 7.5.12version 7.8.12version 7.3.3version 7.7.1version 6.8.2version 7.3.4version 7.4.2version 6.7.35version 6.9.1version 7.6.2version 7.5.3version 7.7.2version 6.9.2version 7.9.1version 7.10.1version 7.8.2version 7.5.4version 6.5.33version 7.8.22version 7.7.21version 7.9.2version 7.3.5version 7.5.5version 7.11.1version 7.9.21version 7.10.2version 24.1.1version 7.6.3version 7.3.6version 7.5.52version 7.11.2version 24.2.1version 24.1.2version 24.2.11version 24.3.1version 24.4.1version 24.2.2version 7.8.23version 7.11.21version 24.2.20version 24.3.2version 24.4.10version 6.5.35version 25.1.1version 24.4.2version 24.3.20version 24.4.15version 25.2.1version 6.5.351version 25.1.2version 24.3.30version 25.3.1version 6.5.352version 24.4.30version 24.2.21version 25.4.1version 25.2.2version 25.2.15version 7.2.0version 7.0.0version 25.2.30version 6.5.353version 25.1.30	Vulnerable	CVE Program (cve.org) e CISA ADP
Cisco	Ios Xr	< 25.2.21≥ 25.3.1 and < 25.4.2	Vulnerable	NIST National Vulnerability Database

Attack characteristics

The CVSS vector, decoded. It describes the attack, not your exposure to it.

Attack vector

Local

Attack complexity

Low

Privileges required

Low

User interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Every base score collected

Sources score independently and may disagree; each row says who scored it and under which version.

Score	Version	Severity	Expl.	Impact	Scored by
8.8	CVSS 3.1	High	2.0	6.0	psirt@cisco.com via NIST National Vulnerability Database
8.8	CVSS 3.1	High	—	—	cisco via CVE Program (cve.org) e CISA ADP

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H (score shown at the top: psirt@cisco.com)

Weakness MITRE

Weakness class according to MITRE’s CWE catalog.

CWE-78 · OS Command Injection

Other CVEs with this weakness →

EPSS over time FIRST

Oct 13, 2026 → Oct 14, 2026 · 2 reading(s) · max 0.18%

Detection

Read off the CVSS vector and the weakness class. Starting points, not tested rules.

Local/physical vector: focus on endpoint telemetry (EDR) from affected hosts.
Look for parameters with command/query metacharacters and unexpected child processes of the service.

endpoint telemetry (EDR)application logs

Timeline

What happened to this CVE, newest first.

2026
Affected products added · cisco/cisco ios xr software
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
SSVC assessment updated
Oct 13, 2026 · CVE Program (cve.org) e CISA ADP
Record published
Oct 13, 2026
CVSS changed · 8.8
Oct 13, 2026 · NIST National Vulnerability Database
Source status changed · → Analyzed
Oct 13, 2026 · NIST National Vulnerability Database
Record created in this database
Oct 13, 2026 · NIST National Vulnerability Database
CVE published
Mar 11, 2026 · cisco

Source activity

Repeated readings are counted rather than listed.

1× Official description updated · Oct 13, 2026 – Oct 13, 2026

References

1 on the record

sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-privesc-
Vendor Advisory, NIST National Vulnerability Database

Elsewhere on this site

Cisco
every CVE for this vendor

Injection
same class

CWE-78
other pages naming this weakness

Related CVEs (same products)

Medium CVE-2026-20118 Cisco IOS-XR NCS 5500 and NCS 5700 Egress Packet Network Interfaces Aligner Interrupt Denial of Service Vulnerability Mar 11, 2026
High CVE-2026-20046 Cisco IOS XR Software CLI Privilege Escalation Vulnerability Mar 11, 2026
High CVE-2026-20074 Cisco IOS XR Software Multi-Instance Intermediate System-to-Intermediate System Denial of Service Vulnerability Mar 11, 2026
High CVE-2023-44487 HTTP/2 Rapid Reset Attack Vulnerability KEV Oct 10, 2023
Medium CVE-2022-20821 Cisco IOS XR Open Port Vulnerability KEV May 26, 2022
High CVE-2020-3569 Cisco IOS XR Software DVMRP Memory Exhaustion Vulnerability KEV Sep 22, 2020

Not in any source we poll

Listed rather than left blank: an empty field and an unmeasured one look identical on screen, and only one is a reason to look elsewhere.

No fixed version, patch or mitigation documented.
No confirmed IOCs, IP addresses, domains, file hashes, or malware artifacts supplied.
No organization-specific asset inventory, compensating-control status, or patch deployment evidence supplied.
No exploit packet captures, log samples, or incident case IDs supplied.

Answered from this record

Text assembled only from the fields above — no additional claims.

What should defenders know first?

CVE-2026-20040 is "Cisco IOS XR Software CLI Privilege Escalation Vulnerability", rated High. It affects Cisco IOS XR Software (Cisco); versions are in the scope table. It is not in CISA KEV, which does not rule out exploitation. CVSS 8.8 describes technical severity. EPSS 0.18% estimates the probability of exploitation in 30 days; neither replaces your asset context. First verify whether exposed or business-critical assets run the affected versions, apply vendor fixes or mitigations, and preserve logs for review.

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