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CVE-2021-39134

Vulnerability in @npmcli/arborist (CVE-2021-39134)

Summary

Vulnerability in @npmcli/arborist (CVE-2021-39134). Confidential information can be exposed externally. Exploitable via node_modules. Mitigation: upgrade to 2.8.2 or later.

Original description

The description as published by the source.

Impact

Arbitrary File Creation, Arbitrary File Overwrite, Arbitrary Code Execution

@npmcli/arborist, the library that calculates dependency trees and manages the node_modules folder hierarchy for the npm command line interface, aims to guarantee that package dependency contracts will be met, and the extraction of package contents will always be performed into the expected folder.

This is, in part, accomplished by resolving dependency specifiers defined in package.json manifests for dependencies with a specific name, and nesting folders to resolve conflicting dependencies.

When multiple dependencies differ only in the case of their name, Arborist's internal data structure saw them as separate items that could coexist within the same level in the node_modules hierarchy. However, on case-insensitive file systems (such as macOS and Windows), this is not the case. Combined with a symlink dependency such as file:/some/path, this allowed an attacker to create a situation in which arbitrary contents could be written to any location on the filesystem.

For example, a package pwn-a could define a dependency in their package.json file such as "foo": "file:/some/path". Another package, pwn-b could define a dependency such as FOO: "file:foo.tgz". On case-insensitive file systems, if pwn-a was installed, and then pwn-b was installed afterwards, the contents of foo.tgz would be written to /some/path, and any existing contents of /some/path would be…

Source: OSV.dev (Open Source Vulnerabilities) NVD GitHub Advisory 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-2021-39134 has been found in @npmcli/arborist.
Attackers can target a specific entry point like node_modules over the network to misuse the product.
Confidential information can be exposed externally.
What to do: upgrade @npmcli/arborist to 2.8.2 or later.
If unsure, ask your IT team or search "@npmcli/arborist CVE-2021-39134" on the vendor's site.

CVE-2021-39134 (@npmcli/arborist) — CWE-178
Attack vector: local / unauthenticated
Attack surface: node_modules / foo.tgz / children
Patched: 2.8.2 — 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 (CWE-178) exists in @npmcli/arborist. Attackers reach the vulnerable code path via node_modules without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of @npmcli/arborist. Attack surface: node_modules / foo.tgz / children.

🔥 Severity

Severity: ?. Confidential information can be exposed externally.

🔧 How to fix

Update to 2.8.2.

🛡️ 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 '@npmcli/arborist' . 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. 1
    Identify exposure identify 
    grep -r '@npmcli/arborist' . | 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 @npmcli/arborist を grep し、稼働しているサービス・バージョンを把握する。

  2. 2
    Apply patch patch 
    Upgrade @npmcli/arborist to 2.8.2

    ステージング環境で 2.8.2 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. 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

npm @npmcli/arborist
[{"type":"SEMVER","events":[{"introduced":"0"},{"fixed":"2.8.2"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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