# SUSE-SU-2021:1636-1: Recommended update for grub2

> An error in the shim_lock protocol on aarch64 systems allows bypassing Secure Boot protections, requiring a bootloader update.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 19 May 2021

## What is SUSE-SU-2021:1636-1?

SUSE-SU-2021:1636-1 is a vulnerability in grub2, published on 19 May 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

This update for grub2 fixes the following issues:

- Fixed error with the shim_lock protocol that is not found on aarch64 (bsc#1185580).

## Which versions are affected by SUSE-SU-2021:1636-1?


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `grub2` | SUSE:Linux Enterprise Micro 5.0 | All versions | 2.04-9.45.2 |
| `grub2` | SUSE:Linux Enterprise Module for Basesystem 15 SP2 | All versions | 2.04-9.45.2 |
| `grub2` | SUSE:Linux Enterprise Module for Server Applications 15 SP2 | All versions | 2.04-9.45.2 |

## How do I fix SUSE-SU-2021:1636-1?

Apply the vendor's patch.

## Is SUSE-SU-2021:1636-1 being exploited?

There is no known exploitation of SUSE-SU-2021:1636-1 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for SUSE-SU-2021:1636-1 and fix it if it is affected.

What it is: SUSE-SU-2021:1636-1 is a vulnerability in grub2, published on 19 May 2021. 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 SUSE-SU-2021:1636-1 in the wild and no public exploit code.

Affected product: grub2. 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/SUSE-SU-2021-1636-1/ (Markdown: https://insights.sbomify.com/SUSE-SU-2021-1636-1/index.md)
```

## Sources

- OSV: https://osv.dev/vulnerability/SUSE-SU-2021:1636-1

---
From sbomify Insights: https://insights.sbomify.com/SUSE-SU-2021-1636-1/
Summaries are generated and may contain mistakes; the official description above is the record.