# CVE-2019-1736: Multiple Cisco UCS-Based Products UEFI Secure Boot Bypass Vulnerability

> An authenticated physical attacker can bypass UEFI Secure Boot to load compromised firmware images on Cisco UCS servers.

- **Severity:** Medium 6.2 (`CVSS:3.0/AV:P/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 23 Sep 2020
- **Updated:** 13 Nov 2024
- **Also known as:** GHSA-pwvv-633w-65j9

## What is CVE-2019-1736?

CVE-2019-1736 is a medium-severity vulnerability in Cisco Identity Services Engine, published on 23 Sep 2020. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A vulnerability in the firmware of the Cisco UCS C-Series Rack Servers could allow an authenticated, physical attacker to bypass Unified Extensible Firmware Interface (UEFI) Secure Boot validation checks and load a compromised software image on an affected device. The vulnerability is due to improper validation of the server firmware upgrade images. An attacker could exploit this vulnerability by installing a server firmware version that would allow the attacker to disable UEFI Secure Boot. A successful exploit could allow the attacker to bypass the signature validation checks that are done by UEFI Secure Boot technology and load a compromised software image on the affected device. A compromised software image is any software image that has not been digitally signed by Cisco.

Weakness: CWE-347 (Improper Verification of Cryptographic Signature)

## Which versions are affected by CVE-2019-1736?

It affects 22 products.


Products: Cisco Fmc1000-K9 Bios, Cisco Fmc1000-K9 Firmware, Cisco Fmc2500-K9 Bios, Cisco Fmc2500-K9 Firmware, Cisco Fmc4500-K9 Bios, Cisco Fmc4500-K9 Firmware, Cisco Identity Services Engine, Cisco Sns-3515-K9 Bios, Cisco Sns-3515-K9 Firmware, Cisco Sns-3595-K9 Bios, Cisco Sns-3595-K9 Firmware, Cisco Sns-3615-K9 Bios, Cisco Sns-3615-K9 Firmware, Cisco Sns-3655-K9 Bios, Cisco Sns-3655-K9 Firmware, Cisco Sns-3695-K9 Bios, Cisco Sns-3695-K9 Firmware, Cisco Tg5004-K9-Rf Bios, Cisco Tg5004-K9-Rf Firmware, Cisco Tg5004-K9 Bios and 2 more.

## How do I fix CVE-2019-1736?

No fix has been published for CVE-2019-1736 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-1736 being exploited?

There is no known exploitation of CVE-2019-1736 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-1736 and fix it if it is affected.

What it is: CVE-2019-1736 is a medium-severity vulnerability in Cisco Identity Services Engine, published on 23 Sep 2020. 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-2019-1736 in the wild and no public exploit code.

Affected product: Cisco Identity Services Engine. 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-2019-1736/ (Markdown: https://insights.sbomify.com/CVE-2019-1736/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-1736
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-1736
- OSV: https://osv.dev/vulnerability/CVE-2019-1736

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From sbomify Insights: https://insights.sbomify.com/CVE-2019-1736/
Summaries are generated and may contain mistakes; the official description above is the record.