CVE-2026-20293: A vulnerability in the Unified Extensible Firmware Interface (UEFI) Shell implementation of Cisco UCS Servers

Routine

HIGH 7.1DOWNGRADEMITIGATEMITIGATE

CVE-2026-20293 is a high-severity flaw (CVSS 7.1) affecting enterprise nfv infrastructure software, unified computing system, unified computing system e-series software. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

A vulnerability in the Unified Extensible Firmware Interface (UEFI) Shell implementation of Cisco UCS Servers and UCS-based appliances could allow an authenticated attacker with valid credentials for a user account with the role of user or admin or an unauthenticated attacker with physical access to an affected device to bypass UEFI Secure Boot validation checks and execute unauthorized software. This vulnerability is due to the availabil

Why this priority

High severity

No fix is published yet: follow the downgrade or mitigation steps.

Risk facts

CVSS score	7.1 (High)
Attack vector	Local
Attack complexity	Low
Privileges needed	Low
User interaction	None
EPSS exploit chance	0.2% (top 94%)
CISA exploited list	No
Weakness	CWE-749
Published	2026-09-08
Last modified	2026-10-26

Publisher (CNA): Cisco Systems, Inc. · Vendor: cisco

Last updated 2026-10-26 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2026-09-08 17:17 UTCPublished CVE record published
2026-10-26 20:22 UTCUpdated Record last modified

cisco enterprise nfv infrastructure software DOWNGRADE

Affected: 3.3.1 · 3.4.1 · 3.5.1 · 3.5.2 · 3.6.1 · 3.6.2 · 3.6.3 · 3.7.1

Fixed in: no fixed release known

Safe to downgrade to: a release before 3.3.1

1. Check installed version

apt-cache policy enterprise-nfv-infrastructure-software || rpm -q enterprise-nfv-infrastructure-software || enterprise-nfv-infrastructure-software --version

2. No fixed release: DOWNGRADE to a release before 3.3.1 (Debian / Ubuntu)

apt-cache madison enterprise-nfv-infrastructure-software sudo apt install enterprise-nfv-infrastructure-software=<VERSION_BEFORE_3.3.1> sudo apt-mark hold enterprise-nfv-infrastructure-software

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list enterprise-nfv-infrastructure-software sudo dnf downgrade enterprise-nfv-infrastructure-software-<VERSION_BEFORE_3.3.1> sudo dnf versionlock add enterprise-nfv-infrastructure-software

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

cisco unified computing system MITIGATE

Affected: 4.0\(1a\) · 4.0\(1b\) · 4.0\(1c\) · 4.0\(1d\) · 4.0\(2a\) · 4.0\(2b\) · 4.0\(2d\) · 4.0\(2e\)

Fixed in: no fixed release known

Safe to downgrade to: no unaffected older release

1. Check installed version

apt-cache policy unified-computing-system || rpm -q unified-computing-system || unified-computing-system --version

No fixed or unaffected release known

Apply the vendor mitigation from the advisory, disable the affected feature, or restrict network access.

cisco unified computing system e-series software MITIGATE

Affected: 4.11.1 · 4.12.1 · 4.12.2 · 4.15.2 · 4.15.3 · 4.15.4

Fixed in: no fixed release known

Safe to downgrade to: a release before 4.11.1

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 UCS and UCS-Based Appliances UEFI Shell Secure Boot Bypass Vulnerability 2026-10-13

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.

Quick answers

How do I fix CVE-2026-20293?

enterprise nfv infrastructure software: downgrade or apply the listed mitigation; unified computing system: mitigate or apply the listed mitigation; unified computing system e-series software: mitigate or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2026-20293 being exploited?

CVE-2026-20293 is not on the CISA Known Exploited Vulnerabilities list at the time of the last update. Check again, as this can change.

What does CVE-2026-20293 affect?

CVE-2026-20293 affects enterprise nfv infrastructure software, unified computing system, unified computing system e-series software. Severity is high (CVSS 7.1). A vulnerability in the Unified Extensible Firmware Interface (UEFI) Shell implementation of Cisco UCS Servers and UCS-based appliances could allow an authenticated attacker with valid credentials for a user account with the role of user or

How urgent is CVE-2026-20293?

Priority 26/100. High severity

Software pages

Cisco vulnerabilities

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References

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