# CVE-2026-20293: Cisco UCS and UCS-Based Appliances UEFI Shell Secure Boot Bypass Vulnerability

> Attackers can bypass UEFI Secure Boot to execute unauthorized software on Cisco UCS servers via shell memory write commands.

- **Severity:** High 7.1 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 8 Sep 2026
- **Updated:** 16 Sep 2026
- **Also known as:** GHSA-xv95-6ccg-fmwj

## What is CVE-2026-20293?

CVE-2026-20293 is a high-severity vulnerability in Cisco Unified Computing System, published on 8 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

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 availability of memory write commands in the UEFI Shell while UEFI Secure Boot is enabled on a device. An attacker could exploit this vulnerability by selecting the UEFI Shell boot option at boot time and using available shell commands to modify UEFI memory variables. A successful exploit could allow the attacker to manipulate the preboot environment, overwrite UEFI Secure Boot-related memory values, and execute unauthorized software on the affected device.

Weakness: CWE-749 (Exposed Dangerous Method or Function)

## Which versions are affected by CVE-2026-20293?

It affects 3 products.


Products: Cisco Enterprise Nfv Infrastructure Software, Cisco Unified Computing System, Cisco Unified Computing System E-Series Software.

## How do I fix CVE-2026-20293?

No fix has been published for CVE-2026-20293 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-20293 being exploited?

There is no known exploitation of CVE-2026-20293 in the wild and no public exploit code.

## Other vulnerabilities in Cisco Unified Computing System

- [CVE-2022-20777](https://insights.sbomify.com/CVE-2022-20777/): Cisco Enterprise NFV Infrastructure Software Vulnerabilities (critical 9.9)
- [CVE-2022-20779](https://insights.sbomify.com/CVE-2022-20779/): Cisco Enterprise NFV Infrastructure Software Vulnerabilities (critical 9.9)
- [CVE-2022-20780](https://insights.sbomify.com/CVE-2022-20780/): Cisco Enterprise NFV Infrastructure Software Vulnerabilities (critical 9.9)
- [CVE-2021-34746](https://insights.sbomify.com/CVE-2021-34746/): Cisco Enterprise NFV Infrastructure Software Authentication Bypass Vulnerability (critical 9.8)
- [CVE-2020-3470](https://insights.sbomify.com/CVE-2020-3470/): Cisco Integrated Management Controller Multiple Remote Code Execution Vulnerabilities (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-20293 and fix it if it is affected.

What it is: CVE-2026-20293 is a high-severity vulnerability in Cisco Unified Computing System, published on 8 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-20293 in the wild and no public exploit code.

Affected product: Cisco Unified Computing System. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-20293/ (Markdown: https://insights.sbomify.com/CVE-2026-20293/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-20293
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-20293
- OSV: https://osv.dev/vulnerability/CVE-2026-20293

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-20293/
Summaries are generated and may contain mistakes; the official description above is the record.