PatchTheCEVCVE-2026-20271: As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco IOS XE Software eng
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This month
HIGH 8.6REMOTEMITIGATE
CVE-2026-20271 is a high-severity flaw (CVSS 8.6) affecting ios xe. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.
As part of Cisco's ongoing commitment to proactive security and product quality, the Cisco IOS XE Software engineering team has conducted a comprehensive internal security review. This review resulted in software hardening releases that address multiple internally discovered vulnerabilities. The vulnerabilities tracked by CVE-2026-20271 are related to insufficient control flow management issues that are grouped under the Common Weakness Enumer
Why this priority
- High severity
- Remotely exploitable, no login, no user action
No fix is published yet: follow the downgrade or mitigation steps.
Risk facts
| CVSS score | 8.6 (High) |
| Attack vector | Network (remote) |
| Attack complexity | Low |
| Privileges needed | None |
| User interaction | None |
| EPSS exploit chance | 0.5% (top 60%) |
| CISA exploited list | No |
| Weakness | CWE-691 |
| Published | 2026-08-05 |
| Last modified | 2026-10-23 |
Publisher (CNA): Cisco Systems, Inc. · Vendor: cisco
Am I affected?
Timeline
- Published CVE record published
- Updated Record last modified
cisco ios xe MITIGATE
Affected: 16.6.2 · 16.6.3 · 16.6.4 · 16.6.4a · 16.6.4s · 16.6.5 · 16.6.5a · 16.6.5b
Fixed in: no fixed release known
Safe to downgrade to: a release before 16.6.2
Check your OS release
cat /etc/os-release; uname -r
Debian / Ubuntu
sudo apt update && sudo apt full-upgrade
RHEL / Amazon Linux / Fedora
sudo dnf upgrade --refresh
Windows
Install the latest cumulative update from Windows Update
If no patch exists yet
OS downgrades are not safe. Apply the vendor mitigation from the advisory and restrict exposure.
Advisories and coverage
Official advisories
- Cisco Security Advisories: Cisco IOS XE Software Security Hardening Release: August 2026 2026-10-02
Verify at the official source NVD · CVE Program · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.
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