Vulnerability in grub2-signed (USN-6355-1)

Summary

vulnerability in grub2-signed (USN-6355-1). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to `1.187.3~20.04.1` or later.

AI summary snake-internal / snake-material-v2

A vulnerability tracked as **USN-6355-1** has been found in grub2-signed. Risk of unauthorized operations or information disclosure. CVSS score: ?/10. What to do: upgrade grub2-signed to **1.187.3~20.04.1** or later. If unsure, ask your IT team or search "grub2-signed USN-6355-1" on the vendor's site.

USN-6355-1 (grub2-signed) — Patched: `1.187.3~20.04.1` — apply immediately Plan: 1) Audit SBOM/dependencies, 2) Stage→prod upgrade, 3) Add WAF/proxy monitoring on affected endpoints, 4) Hunt IOCs in logs. Refs: see the GHSA / vendor advisory / patched release linked on this page.

❓ What is the problem

**A vulnerability** (unclassified) exists in grub2-signed.

📍 Affected scope

grub2-signed — .

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure

🔧 How to fix

Update to **1.187.3~20.04.1**.

🛡️ Workaround

Until the patch is applied: disable the affected feature, apply WAF rules, or restrict access via network ACLs.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'grub2-signed' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response Actions (7 steps)

Concrete steps and command examples for SOC/SRE teams to execute in order

1
Identify exposure identify
```
grep -r 'grub2-signed' . | grep -v node_modules
```
リポジトリと本番環境の依存ファイル (package-lock.json / requirements.txt / go.sum / Gemfile.lock 等) で `grub2-signed` を grep し、稼働しているサービス・バージョンを把握する。
6
Apply patch patch
```
Upgrade grub2-signed to 1.187.3~20.04.1
```
ステージング環境で 1.187.3~20.04.1 に上げて回帰テスト → 本番反映。回帰テストはアプリの主要ハッピーパスと、Step 3 で見つけた異常検知の続報チェックを含めること。
7
Post-deployment verification verify
```
Confirm patched version is live in production
```
パッチ適用後、ステージングで PoC または同等の悪用パターンを再現して脆弱性が閉じたことを確認。本番では Step 3 と同じログクエリでアラート再発が無いか継続監視。

Affected packages

Ubuntu:20.04:LTS grub2-signed

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.187.3~20.04.1"}]}]

Ubuntu:20.04:LTS grub2-unsigned

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.06-2ubuntu14.1"}]}]

Ubuntu:20.04:LTS shim

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"15.7-0ubuntu1"}]}]

Ubuntu:20.04:LTS shim-signed

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.40.9"}]}]

Ubuntu:22.04:LTS grub2-signed

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.187.3~22.04.1"}]}]

Ubuntu:22.04:LTS grub2-unsigned

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.06-2ubuntu14.1"}]}]

Ubuntu:22.04:LTS shim

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"15.7-0ubuntu1"}]}]

Ubuntu:22.04:LTS shim-signed

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"1.51.3"}]}]

References

advisory https://ubuntu.com/security/notices/USN-6355-1
report https://ubuntu.com/security/CVE-2021-3695
report https://ubuntu.com/security/CVE-2021-3696
report https://ubuntu.com/security/CVE-2021-3697
report https://ubuntu.com/security/CVE-2021-3981
report https://ubuntu.com/security/CVE-2022-3775
report https://ubuntu.com/security/CVE-2022-28733
report https://ubuntu.com/security/CVE-2022-28734
report https://ubuntu.com/security/CVE-2022-28735
report https://ubuntu.com/security/CVE-2022-28736
report https://ubuntu.com/security/CVE-2022-28737
report https://launchpad.net/bugs/2029518