This page tracks the Ubuntu fix status. The vulnerability itself is described on the main CVE page. View CVE-2021-47555 →

UBUNTU-CVE-2021-47555

Vulnerability in linux-hwe-edge (UBUNTU-CVE-2021-47555)

Summary

Vulnerability in linux-hwe-edge (UBUNTU-CVE-2021-47555). Risk of unauthorized operations or information disclosure. Mitigation: upgrade to 5.4.0-1066.69~18.04.1 or later.

Original description

The description as published by the source.

In the Linux kernel, the following vulnerability has been resolved: net: vlan: fix underflow for the real_dev refcnt Inject error before dev_hold(real_dev) in register_vlan_dev(), and execute the following testcase: ip link add dev dummy1 type dummy ip link add name dummy1.100 link dummy1 type vlan id 100 ip link del dev dummy1 When the dummy netdevice is removed, we will get a WARNING as following: ======================================================================= refcount_t: decrement hit 0; leaking memory. WARNING: CPU: 2 PID: 0 at lib/refcount.c:31 refcount_warn_saturate+0xbf/0x1e0 and an endless loop of: ======================================================================= unregister_netdevice: waiting for dummy1 to become free. Usage count = -1073741824 That is because dev_put(real_dev) in vlan_dev_free() be called without dev_hold(real_dev) in register_vlan_dev(). It makes the refcnt of real_dev underflow. Move the dev_hold(real_dev) to vlan_dev_init() which is the call-back of ndo_init(). That makes dev_hold() and dev_put() for vlan's real_dev symmetrical.

Source: OSV.dev (Open Source Vulnerabilities) OSV

Auto-generated summary

Assembled by SecPulse from the source data (CVSS, CWE, affected versions) using templates — no AI involved. Check the original description and references below for exact details.

A vulnerability tracked as UBUNTU-CVE-2021-47555 has been found in linux-hwe-edge.
Risk of unauthorized operations or information disclosure.
What to do: upgrade linux-hwe-edge to 5.4.0-1066.69~18.04.1 or later.
If unsure, ask your IT team or search "linux-hwe-edge UBUNTU-CVE-2021-47555" on the vendor's site.

UBUNTU-CVE-2021-47555 (linux-hwe-edge)
Attack vector: local / no user interaction
Patched: 5.4.0-1066.69~18.04.1 — 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-hwe-edge.

📍 Affected scope

Check the vendor advisory for the affected versions of linux-hwe-edge.

🔥 Severity

Severity: ?. Risk of unauthorized operations or information disclosure.

🔧 How to fix

Update to 5.4.0-1066.69~18.04.1.

🛡️ 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-hwe-edge' . against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response actions

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

1
Identify exposure identify
```
grep -r 'linux-hwe-edge' . | 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-hwe-edge を grep し、稼働しているサービス・バージョンを把握する。
2
Apply patch patch
```
Upgrade linux-hwe-edge to 5.4.0-1066.69~18.04.1
```
ステージング環境で 5.4.0-1066.69~18.04.1 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を含めること。
3
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。本番ではアクセスログ・WAF でアラート再発が無いか継続監視。

Affected packages

Ubuntu:16.04:LTS linux-hwe-edge

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

Ubuntu:18.04:LTS linux-aws-5.4

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1066.69~18.04.1"}]}]

Ubuntu:18.04:LTS linux-azure-5.4

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1070.73~18.04.1"}]}]

Ubuntu:18.04:LTS linux-gcp-5.4

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1065.69~18.04.1"}]}]

Ubuntu:18.04:LTS linux-hwe-5.4

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-100.113~18.04.1"}]}]

Ubuntu:18.04:LTS linux-ibm-5.4

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1015.16~18.04.1"}]}]

Ubuntu:18.04:LTS linux-oracle-5.4

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1064.68~18.04.1"}]}]

Ubuntu:18.04:LTS linux-raspi-5.4

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1053.60~18.04.1"}]}]

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: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:18.04:LTS linux-gcp-5.3

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

Ubuntu:18.04:LTS linux-gke-4.15

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

Ubuntu:18.04:LTS linux-gke-5.4

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

Ubuntu:18.04:LTS linux-gkeop-5.4

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

Ubuntu:18.04:LTS linux-hwe

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

Ubuntu:18.04:LTS linux-oem

[{"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:20.04:LTS linux

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-100.113"}]}]

Ubuntu:20.04:LTS linux-aws

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1066.69"}]}]

Ubuntu:20.04:LTS linux-azure

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1070.73"}]}]

Ubuntu:20.04:LTS linux-bluefield

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1028.31"}]}]

Ubuntu:20.04:LTS linux-gcp

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1065.69"}]}]

Ubuntu:20.04:LTS linux-gkeop

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1034.35"}]}]

Ubuntu:20.04:LTS linux-ibm

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1015.16"}]}]

Ubuntu:20.04:LTS linux-kvm

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1056.58"}]}]

Ubuntu:20.04:LTS linux-oracle

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1064.68"}]}]

Ubuntu:20.04:LTS linux-raspi

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1053.60"}]}]

Ubuntu:20.04:LTS linux-aws-5.11

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

Ubuntu:20.04:LTS linux-aws-5.13

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

Ubuntu:20.04:LTS linux-aws-5.8

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

Ubuntu:20.04:LTS linux-azure-5.11

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

Ubuntu:20.04:LTS linux-azure-5.13

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

Ubuntu:20.04:LTS linux-azure-5.8

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

Ubuntu:20.04:LTS linux-azure-fde

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

Ubuntu:20.04:LTS linux-gcp-5.11

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

Ubuntu:20.04:LTS linux-gcp-5.13

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

Ubuntu:20.04:LTS linux-gcp-5.8

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

Ubuntu:20.04:LTS linux-gke

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

Ubuntu:20.04:LTS linux-gke-5.15

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

Ubuntu:20.04:LTS linux-hwe-5.11

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

Ubuntu:20.04:LTS linux-hwe-5.13

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

Ubuntu:20.04:LTS linux-hwe-5.8

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

Ubuntu:20.04:LTS linux-intel-5.13

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

Ubuntu:20.04:LTS linux-oem-5.10

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

Ubuntu:20.04:LTS linux-oem-5.13

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

Ubuntu:20.04:LTS linux-oem-5.14

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

Ubuntu:20.04:LTS linux-oem-5.6

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

Ubuntu:20.04:LTS linux-oracle-5.11

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

Ubuntu:20.04:LTS linux-oracle-5.13

[{"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-5.11

[{"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-fips

[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"5.4.0-1043.49"}]}]

Ubuntu:22.04:LTS linux-allwinner-5.19

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

Ubuntu:22.04:LTS linux-aws-5.19

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

Ubuntu:22.04:LTS linux-aws-6.2

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

Ubuntu:22.04:LTS linux-azure-5.19

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

Ubuntu:22.04:LTS linux-azure-6.2

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

Ubuntu:22.04:LTS linux-azure-fde-5.19

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

Ubuntu:22.04:LTS linux-azure-fde-6.2

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

Ubuntu:22.04:LTS linux-gcp-5.19

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

Ubuntu:22.04:LTS linux-gcp-6.2

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

Ubuntu:22.04:LTS linux-hwe-5.19

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

Ubuntu:22.04:LTS linux-hwe-6.2

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

Ubuntu:22.04:LTS linux-intel-iot-realtime

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

Ubuntu:22.04:LTS linux-lowlatency-hwe-5.19

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

Ubuntu:22.04:LTS linux-lowlatency-hwe-6.2

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

Ubuntu:22.04:LTS linux-nvidia-6.2

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

Ubuntu:22.04:LTS linux-oem-5.17

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

Ubuntu:22.04:LTS linux-oem-6.0

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

Ubuntu:22.04:LTS linux-oem-6.1

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

Ubuntu:22.04:LTS linux-realtime

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

Ubuntu:22.04:LTS linux-riscv

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

Ubuntu:22.04:LTS linux-riscv-5.19

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

Ubuntu:22.04:LTS linux-starfive-5.19

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

Ubuntu:22.04:LTS linux-starfive-6.2

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

Ubuntu:24.04:LTS linux-raspi-realtime

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

References

report ubuntu.com
report cve.org
report git.kernel.org
report git.kernel.org
report git.kernel.org
report git.kernel.org
report git.kernel.org