Out-of-Bounds Write in Linux Kernel (CVE-2021-3501, CVSS 7.1)

Summary

Out-of-bounds write in Linux Kernel (CVE-2021-3501). Data can be tampered with by attackers.

Original description

The description as published by the source.

A flaw was found in the Linux kernel in versions before 5.12. The value of internal.ndata, in the KVM API, is mapped to an array index, which can be updated by a user process at anytime which could lead to an out-of-bounds write. The highest threat from this vulnerability is to data integrity and system availability.

Source: NIST National Vulnerability Database NVD GitHub Advisory

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-2021-3501 has been found in Linux Kernel.
Data can be tampered with by attackers. CVSS score: 7.1/10.
What to do: apply the vendor's official patched release.
If unsure, ask your IT team or search "Linux Kernel CVE-2021-3501" on the vendor's site.

CVE-2021-3501 (Linux Kernel) — CWE-787 / CVSS v3 7.1
Attack vector: local / 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

Out-of-bounds write (CWE-787) exists in Linux Kernel.

📍 Affected scope

Check the vendor advisory for the affected versions of Linux Kernel.

🔥 Severity

Severity: High (CVSS 7.1/10). Data can be tampered with by attackers.

🔧 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 Linux Kernel を使っているサービスとバージョンを洗い出す。
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

Debian DEBIAN-CVE-2021-3501 linux Fixed in: 5.10.38-1

Out-of-Bounds Write in Linux Kernel (CVE-2021-3501)

Summary

Original description

Auto-generated summary

Response actions

Fix status by distribution

References