Is CVE-2026-20279 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-20279 being exploited in the wild.

How severe is CVE-2026-20279?

Critical severity, with a CVSS score of 9.8, published 2 September 2026.

Which products and versions are affected?

Cisco IOS XR Software all releases including IOS XR7 (LNT).

Is there a fix for CVE-2026-20279?

No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

How is CVE-2026-20279 attacked?

It is attacked over the network, in an operating system.

Am I affected by CVE-2026-20279?

Check whether you run Cisco IOS XR Software 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-2026-20279: Cisco IOS XR Software improper access control

CVE-2026-20279 · Severity: critical · CVSS 9.8 · Published 2026-09-02

Cisco IOS XR Software is a core operating system used in enterprise routers and network infrastructure devices. Multiple internal security vulnerabilities related to improper access control and resource handling were discovered and addressed in a software hardening release. These flaws could allow attackers to bypass authentication, gain unauthorized access, or cause service disruption on affected network devices.

Technologies: Cisco IOS XR Software. Vendors: Cisco.

Quick answers

Is CVE-2026-20279 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-20279 being exploited in the wild.
How severe is CVE-2026-20279?: Critical severity, with a CVSS score of 9.8, published 2 September 2026.
Which products and versions are affected?: Cisco IOS XR Software all releases including IOS XR7 (LNT).
Is there a fix for CVE-2026-20279?: No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
How is CVE-2026-20279 attacked?: It is attacked over the network, in an operating system.
Am I affected by CVE-2026-20279?: Check whether you run Cisco IOS XR Software 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

This advisory addresses multiple vulnerability classes grouped under CVE-2026-20279, with the primary issue being improper access control (CWE-284), along with related issues in resource control lifetime (CWE-664), incorrect calculations (CWE-682), and insufficient input validation (CWE-707). The vulnerabilities were discovered through internal security review and affect all releases of Cisco IOS XR Software, including IOS XR7 (LNT), regardless of device configuration. The flaws require network access with no authentication or user interaction; a remote attacker can exploit these without privileges to achieve confidentiality, integrity, and availability impacts. Cisco has not reported active exploitation in the wild, but patches and SMUs (Service and Maintenance Upgrades) are available for affected software trains.

Affected products

Cisco IOS XR Software all releases including IOS XR7 (LNT)

Timeline

2026-09-02: disclosed
2026-09-02: advisory: Critical advisory published; Last updated 2026-09-17

References

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