A use-after-free in Busybox's awk applet leads to denial of… (CVE-2021-42378)

Summary

Vulnerability reported (CVE-2021-42378). Successful exploitation can lead to full system takeover.

Original description

The description as published by the source.

A use-after-free in Busybox's awk applet leads to denial of service and possibly code execution when processing a crafted awk pattern in the getvar_i function

Source: OSV.dev (Open Source Vulnerabilities) NVD 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 CVE-2021-42378 has been found.
Successful exploitation can lead to full system takeover.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "CVE-2021-42378" on the vendor's site.

CVE-2021-42378
Attack vector: remote (network-reachable) / no user interaction
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) has been reported.

📍 Affected scope

Check the vendor advisory for the affected versions.

🔥 Severity

Severity: ?. Successful exploitation can lead to full system takeover.

🔧 How to fix

Update to the patched release per vendor advisory.

🛡️ 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. Audit SBOM/dependencies to find affected services.

Response actions

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

1
Identify exposure identify
```
Audit SBOM/dependencies for affected components.
```
資産台帳・SBOM・依存マニフェストで影響コンポーネントを特定する。
2
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。

Fix status by distribution

Fixed packages published by each distribution for this CVE

Alpine Linux ALPINE-CVE-2021-42378 busybox Fixed in: 1.31.1-r11
Debian DEBIAN-CVE-2021-42378 busybox Fixed in: 1:1.35.0-1

A use-after-free in Busybox's awk applet leads to denial of service and possibly code execution when processing a…