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CVE-2026-59947 medium CVSS 4.7

Vulnerability in composer/composer (CVE-2026-59947)

Summary

Vulnerability in composer/composer (CVE-2026-59947). Confidential information can be exposed externally. Mitigation: upgrade to 2.2.29 or later.

Original description

The description as published by the source.

Composer is a dependency Manager for the PHP language. Prior to 2.2.29 and 2.10.2, when Composer is run with -vvv debug verbosity, it could print a credential embedded in the username slot of a repository or package URL, such as a GitHub Personal Access Token in https://TOKEN@host/, to debug output because AuthHelper, Url::sanitize, and ProcessExecutor did not sanitize username-only URL credentials. This issue is fixed in versions 2.2.29 and 2.10.2.

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-2026-59947 has been found in composer/composer.
Confidential information can be exposed externally. CVSS score: 4.7/10.
What to do: upgrade composer/composer to 2.2.29 or later.
If unsure, ask your IT team or search "composer/composer CVE-2026-59947" on the vendor's site.

CVE-2026-59947 (composer/composer) — CWE-532 / CVSS v3 4.7
Attack vector: local / no user interaction
Patched: 2.2.29 — 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-532) exists in composer/composer.

📍 Affected scope

Check the vendor advisory for the affected versions of composer/composer.

🔥 Severity

Severity: Medium (CVSS 4.7/10). Confidential information can be exposed externally.

🔧 How to fix

Update to 2.2.29.

🛡️ 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 '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 patch patch 
    Upgrade composer/composer to 2.2.29

    ステージング環境で 2.2.29 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

composer composer/composer
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.2.29"}]}]
Packagist composer/composer
[{"type":"ECOSYSTEM","events":[{"introduced":"1.0.0"},{"fixed":"2.2.29"}]}]
Bitnami composer
[{"type":"SEMVER","events":[{"introduced":"1.0.0"},{"fixed":"2.2.29"},{"introduced":"2.3.0"},{"fixed":"2.10.2"}]}]

Fix status by distribution

Fixed packages published by each distribution for this CVE

References

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