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UBUNTU-CVE-2021-34556
Vulnerability in linux (UBUNTU-CVE-2021-34556)
Summary
vulnerability in linux (UBUNTU-CVE-2021-34556). Confidential information can be exposed externally. Mitigation: upgrade to `5.4.0-1059.62~18.04.1` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **UBUNTU-CVE-2021-34556** has been found in linux.
Confidential information can be exposed externally. CVSS score: ?/10.
What to do: upgrade linux to **5.4.0-1059.62~18.04.1** or later.
If unsure, ask your IT team or search "linux UBUNTU-CVE-2021-34556" on the vendor's site.
UBUNTU-CVE-2021-34556 (linux) —
Attack vector: local / no user interaction
Patched: `5.4.0-1059.62~18.04.1` — 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 linux.
📍 Affected scope
linux — .
🔥 Severity
Severity: ?. Confidential information can be exposed externally
🔧 How to fix
Update to **5.4.0-1059.62~18.04.1**.
🛡️ 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 'linux' .` 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
-
1Identify exposure identify
grep -r 'linux' . | 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 `linux` を grep し、稼働しているサービス・バージョンを把握する。
-
6Apply patch patch
Upgrade linux to 5.4.0-1059.62~18.04.1ステージング環境で 5.4.0-1059.62~18.04.1 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。
-
7Post-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:Pro:14.04:LTS
linux
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:14.04:LTS
linux-aws
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:14.04:LTS
linux-azure
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:14.04:LTS
linux-lts-xenial
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:16.04:LTS
linux
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:16.04:LTS
linux-aws
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:16.04:LTS
linux-aws-hwe
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:16.04:LTS
linux-azure
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:16.04:LTS
linux-gcp
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:16.04:LTS
linux-hwe
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:16.04:LTS
linux-hwe-edge
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:16.04:LTS
linux-kvm
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:16.04:LTS
linux-oracle
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS:16.04:LTS
linux-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-aws-5.4
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1059.62~18.04.1"}]}]
Ubuntu:18.04:LTS
linux-azure-5.4
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1063.66~18.04.1"}]}]
Ubuntu:18.04:LTS
linux-gcp-5.4
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1057.61~18.04.1"}]}]
Ubuntu:18.04:LTS
linux-gke-5.4
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1055.58~18.04.1"}]}]
Ubuntu:18.04:LTS
linux-gkeop-5.4
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1026.27~18.04.1"}]}]
Ubuntu:18.04:LTS
linux-hwe-5.4
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-90.101~18.04.1"}]}]
Ubuntu:18.04:LTS
linux-oracle-5.4
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1057.61~18.04.1"}]}]
Ubuntu:18.04:LTS
linux-raspi-5.4
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1046.50~18.04.1"}]}]
Ubuntu:Pro:18.04:LTS
linux
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:18.04:LTS
linux-aws
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-aws-5.0
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-aws-5.3
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-azure
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:18.04:LTS
linux-azure-4.15
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-azure-5.3
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-azure-edge
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-gcp
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:18.04:LTS
linux-gcp-4.15
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-gcp-5.3
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-gcp-edge
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-gke-4.15
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-hwe
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-hwe-edge
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:18.04:LTS
linux-kvm
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-oem
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:18.04:LTS
linux-oracle
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-oracle-5.0
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:18.04:LTS
linux-oracle-5.3
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS-updates:18.04:LTS
linux-aws-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS-updates:18.04:LTS
linux-azure-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS-updates:18.04:LTS
linux-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS-updates:18.04:LTS
linux-gcp-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS:18.04:LTS
linux-aws-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS:18.04:LTS
linux-azure-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS:18.04:LTS
linux-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS:18.04:LTS
linux-gcp-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:20.04:LTS
linux
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-90.101"}]}]
Ubuntu:20.04:LTS
linux-aws
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1059.62"}]}]
Ubuntu:20.04:LTS
linux-aws-5.11
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.11.0-1019.20~20.04.1"}]}]
Ubuntu:20.04:LTS
linux-azure
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1063.66"}]}]
Ubuntu:20.04:LTS
linux-azure-5.11
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.11.0-1017.18~20.04.1"}]}]
Ubuntu:20.04:LTS
linux-bluefield
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1021.24"}]}]
Ubuntu:20.04:LTS
linux-gcp
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1057.61"}]}]
Ubuntu:20.04:LTS
linux-gcp-5.11
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.11.0-1020.22~20.04.1"}]}]
Ubuntu:20.04:LTS
linux-gke
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1055.58"}]}]
Ubuntu:20.04:LTS
linux-gkeop
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1026.27"}]}]
Ubuntu:20.04:LTS
linux-hwe-5.11
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.11.0-37.41~20.04.2"}]}]
Ubuntu:20.04:LTS
linux-ibm
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1007.8"}]}]
Ubuntu:20.04:LTS
linux-kvm
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1049.51"}]}]
Ubuntu:20.04:LTS
linux-oem-5.10
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.10.0-1050.52"}]}]
Ubuntu:20.04:LTS
linux-oem-5.13
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.13.0-1014.18"}]}]
Ubuntu:20.04:LTS
linux-oracle
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1057.61"}]}]
Ubuntu:20.04:LTS
linux-oracle-5.11
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.11.0-1019.20~20.04.1"}]}]
Ubuntu:20.04:LTS
linux-raspi
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1046.50"}]}]
Ubuntu:20.04:LTS
linux-riscv-5.11
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.11.0-1020.21~20.04.1"}]}]
Ubuntu:20.04:LTS
linux-aws-5.8
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:20.04:LTS
linux-azure-5.8
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:20.04:LTS
linux-azure-fde-5.15
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:20.04:LTS
linux-gcp-5.8
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:20.04:LTS
linux-hwe-5.8
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:20.04:LTS
linux-oem-5.6
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:20.04:LTS
linux-oracle-5.8
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:20.04:LTS
linux-raspi2
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:20.04:LTS
linux-riscv
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:20.04:LTS
linux-riscv-5.8
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS-updates:20.04:LTS
linux-aws-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1069.73+fips2"}]}]
Ubuntu:Pro:FIPS-updates:20.04:LTS
linux-azure-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1073.76+fips1"}]}]
Ubuntu:Pro:FIPS-updates:20.04:LTS
linux-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1036.42"}]}]
Ubuntu:Pro:FIPS-updates:20.04:LTS
linux-gcp-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1067.71~20.04.1"}]}]
Ubuntu:Pro:FIPS:20.04:LTS
linux-aws-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS:20.04:LTS
linux-azure-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS:20.04:LTS
linux-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:Pro:FIPS:20.04:LTS
linux-gcp-fips
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:22.04:LTS
linux-intel-iot-realtime
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:22.04:LTS
linux-realtime
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:24.04:LTS
linux-raspi-realtime
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
Ubuntu:26.04
linux-nvidia
[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}]
References
- advisory https://ubuntu.com/security/notices/USN-5092-1
- advisory https://ubuntu.com/security/notices/USN-5092-2
- advisory https://ubuntu.com/security/notices/USN-5096-1
- advisory https://ubuntu.com/security/notices/USN-5115-1
- advisory https://ubuntu.com/security/notices/USN-5137-1
- advisory https://ubuntu.com/security/notices/USN-5137-2
- report https://ubuntu.com/security/CVE-2021-34556
- report https://www.openwall.com/lists/oss-security/2021/08/01/3
- report https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch/?id=f5e81d1117501546b7be050c5fbafa6efd2c722c
- report https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/patch/?id=2039f26f3aca5b0e419b98f65dd36481337b86ee
- report https://www.cve.org/CVERecord?id=CVE-2021-34556