Is CVE-2026-20271 exploited in the wild?

No. Junglewise Threat Intelligence has no report of CVE-2026-20271 being exploited in the wild.

How severe is CVE-2026-20271?

High severity, with a CVSS score of 8.6, published 5 August 2026.

Which products and versions are affected?

Cisco IOS XE 17.9, 17.12, 17.15, 17.18, 26.1.

Is there a fix for CVE-2026-20271?

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-2026-20271 attacked?

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

Am I affected by CVE-2026-20271?

Check whether you run Cisco IOS XE 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-2026-20271: Cisco IOS XE insufficient control flow management

CVE-2026-20271 · Severity: high · CVSS 8.6 · Published 2026-08-05

Cisco IOS XE is networking device operating system software used to power switches, routers, and other infrastructure equipment. A vulnerability in control flow management could allow an attacker to cause system instability, service disruption, or other impacts depending on the specific code path exploited. This was discovered during an internal security review and is not currently known to be exploited.

Technologies: Cisco IOS XE. Vendors: Cisco.

Quick answers

Is CVE-2026-20271 exploited in the wild?: No. Junglewise Threat Intelligence has no report of CVE-2026-20271 being exploited in the wild.
How severe is CVE-2026-20271?: High severity, with a CVSS score of 8.6, published 5 August 2026.
Which products and versions are affected?: Cisco IOS XE 17.9, 17.12, 17.15, 17.18, 26.1.
Is there a fix for CVE-2026-20271?: 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-2026-20271 attacked?: It is attacked over the network, in an operating system.
Am I affected by CVE-2026-20271?: Check whether you run Cisco IOS XE 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

CVE-2026-20271 tracks insufficient control flow management issues (CWE-691) found in Cisco IOS XE Software during internal security testing. The vulnerability affects IOS XE in both autonomous and controller modes, with a maximum CVSS score of 8.6 indicating high severity. Attack vector is network-based with no authentication or user interaction required. Cisco has released fixed software versions (17.9.10, 17.12.8, 17.15.6, 17.18.4/4a, and 26.1.2) that address this and related issues. No workarounds are available.

Affected products

Cisco IOS XE 17.9, 17.12, 17.15, 17.18, 26.1

Timeline

2026-08-05: disclosed

References

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