Is CVE-2026-20040 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-20040 being exploited in the wild.

How severe is CVE-2026-20040?

High severity, with a CVSS score of 8.8, published 11 March 2026.

Which products and versions are affected?

Cisco IOS XR All versions prior to 25.2.21, 25.3.1 prior to 25.4.2.

Is there a fix for CVE-2026-20040?

A patch was published on 2026-03-11: Fixed releases 25.2.21 and 25.4.2 made available Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

How is CVE-2026-20040 attacked?

It is attacked with local access, in an operating system.

Am I affected by CVE-2026-20040?

Check whether you run Cisco IOS XR at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

CVE-2026-20040: Cisco IOS XR Software privilege escalation in CLI

CVE-2026-20040 · Severity: high · CVSS 8.8 · Published 2026-03-11

A vulnerability in the command-line interface of Cisco IOS XR Software could allow a user with low-level access to take full control of the device. By entering specially crafted commands, an attacker can bypass security restrictions to execute unauthorized actions with root-level privileges. This could lead to a complete compromise of the networking equipment, allowing the attacker to modify configurations, access sensitive data, or disrupt network operations.

Technologies: Cisco IOS XR. Vendors: Cisco.

Quick answers

Is CVE-2026-20040 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-20040 being exploited in the wild.
How severe is CVE-2026-20040?: High severity, with a CVSS score of 8.8, published 11 March 2026.
Which products and versions are affected?: Cisco IOS XR All versions prior to 25.2.21, 25.3.1 prior to 25.4.2.
Is there a fix for CVE-2026-20040?: A patch was published on 2026-03-11: Fixed releases 25.2.21 and 25.4.2 made available Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-20040 attacked?: It is attacked with local access, in an operating system.
Am I affected by CVE-2026-20040?: Check whether you run Cisco IOS XR at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

Technical details

An OS command injection vulnerability (CWE-78) exists in the Command Line Interface (CLI) of Cisco IOS XR Software due to insufficient validation of user-supplied arguments passed to specific CLI commands. An authenticated, local attacker with low-privileged access can exploit this by executing crafted commands at the prompt. Successful exploitation allows the attacker to escape the restricted CLI environment and execute arbitrary commands on the underlying Linux-based operating system with root privileges. Cisco has released software updates (e.g., 25.2.21 and 25.4.2) to address this issue; no workarounds are available for this specific CVE.

Affected products

Cisco IOS XR Software All versions prior to 25.2.21, 25.3.1 prior to 25.4.2

Timeline

2026-03-11: disclosed: Initial advisory publication by Cisco
2026-03-11: patched: Fixed releases 25.2.21 and 25.4.2 made available

References

https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-iosxr-privesc-bF8D5U4W

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