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CVE-2026-59944 medium CVSS 6.1

Path Traversal in composer/composer (CVE-2026-59944)

Summary

Path traversal in composer/composer (CVE-2026-59944). Confidential information can be exposed externally. Exploitable via vendor. Mitigation: upgrade to 2.2.30 or later.

Original description

The description as published by the source.

Summary

A malicious or compromised Composer package could, when installed as a dependency, cause Composer to change the permissions of a file outside that package's own directory and to register a runnable vendor/bin command that points at that outside file. This is a path traversal and link following issue. It is not remote code execution, the attacker gains no ability to read or receive your data directly. The risk is that a file which was readable only by its owner, but modifiable by Composer, can be made world readable and executable, which is enough to expose its contents on a shared or multi tenant host. The earlier hardening from GHSA-gjfg-22fp-rrxx can be bypassed, since it only rejected literal .. path segments in a package's declared binaries, and was only applied in a single place during dependency resolution.

Am I affected?

You can be affected if a malicious or compromised package, including a transitive dependency, is installed in your project, and either of the following is true:

  • The dependency package ships one of its declared binaries as a symbolic link that resolves to a location outside the package's own directory. Nothing beyond a normal install or update is required.
  • Or, the recorded metadata of your installed dependencies (vendor/composer/installed.json) declares a binary path that escapes the package's directory. Composer regenerates missing binaries from that recorded metadata at the end of an install, and uses this metadata for rein…

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-2026-59944 has been found in composer/composer.
Attackers can target a specific entry point like vendor over the network to misuse the product.
Confidential information can be exposed externally. CVSS score: 6.1/10.
What to do: upgrade composer/composer to 2.2.30 or later.
If unsure, ask your IT team or search "composer/composer CVE-2026-59944" on the vendor's site.

CVE-2026-59944 (composer/composer) — CWE-22 / CVSS v3 6.1
Attack vector: local / unauthenticated
Attack surface: vendor
Patched: 2.2.30 — apply immediately
Workaround: Upgrading is the only complete fix.
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

Path traversal (CWE-22) exists in composer/composer. Attackers reach the vulnerable code path via vendor without authentication.

📍 Affected scope

Check the vendor advisory for the affected versions of composer/composer. Attack surface: vendor.

🔥 Severity

Severity: Medium (CVSS 6.1/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 2.2.30.

🛡️ Workaround

Workaround: Upgrading is the only complete fix.

🔍 Detection

Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'composer/composer' . 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 'composer/composer' . | 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 composer/composer 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 temporary workaround mitigate 
    Upgrading is the only complete fix.

    パッチが適用されるまでの応急処置として、Upgrading is the only complete fix. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 3
    Apply patch patch 
    Upgrade composer/composer to 2.2.30

    ステージング環境で 2.2.30 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。

  4. 4
    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

composer composer/composer
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.2.30"}]}]

References

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