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CVE-2026-59882 medium CVSS 4.2

Vulnerability in guzzlehttp/psr7 (CVE-2026-59882)

Summary

vulnerability in guzzlehttp/psr7 (CVE-2026-59882). Risk of unauthorized operations or information disclosure. Exploitable via ``SERVER_NAME``. Mitigation: upgrade to `2.12.3` or later.

AI summary snake-internal / snake-material-v2

A vulnerability tracked as **CVE-2026-59882** has been found in guzzlehttp/psr7. Attackers can target a specific entry point like ``SERVER_NAME`` over the network to misuse the product. Risk of unauthorized operations or information disclosure. CVSS score: 4.2/10. What to do: upgrade guzzlehttp/psr7 to **2.12.3** or later. If unsure, ask your IT team or search "guzzlehttp/psr7 CVE-2026-59882" on the vendor's site.
CVE-2026-59882 (guzzlehttp/psr7) — CWE-20 / CVSS v3 4.2 Attack vector: remote (network-reachable) / unauthenticated Attack surface: `SERVER_NAME` / `SERVER_ADDR` / `Uri` / `Host` Patched: `2.12.3` — apply immediately Workaround: If you cannot upgrade immediately, validate and normalize host values before you build or modify a `Uri` from untrusted input, and do not treat `Uri::getHost()` as a trust boundary for a host you have not independently checked. 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-20) exists in guzzlehttp/psr7. Attackers reach the vulnerable code path via ``SERVER_NAME`` without authentication.
📍 Affected scope
guzzlehttp/psr7 — . Attack surface: `SERVER_NAME` / `SERVER_ADDR` / `Uri` / `Host`.
🔥 Severity
Severity: Medium (CVSS 4.2/10). Risk of unauthorized operations or information disclosure
🔧 How to fix
Update to **2.12.3**.
🛡️ Workaround
Workaround: If you cannot upgrade immediately, validate and normalize host values before you build or modify a `Uri` from untrusted input, and do not treat `Uri::getHost()` as a trust boundary for a host you have not independently checked.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'guzzlehttp/psr7' .` against your dependency files (package-lock.json, requirements.txt, go.sum) to find affected services.

Response Actions (7 steps)

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

  1. 1
    Identify exposure identify 
    grep -r 'guzzlehttp/psr7' . | 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 `guzzlehttp/psr7` を grep し、稼働しているサービス・バージョンを把握する。

  2. 5
    Apply temporary workaround mitigate 
    If you cannot upgrade immediately, validate and normalize host values before you build or modify a `Uri` from untrusted input, and do not treat `Uri::getHost()` as a trust boundary for a host you have not independently checked.

    パッチが適用されるまでの応急処置として、If you cannot upgrade immediately, validate and normalize host values before you build or modify a `Uri` from untrusted input, and do not treat `Uri::getHost()` as a trust boundary for a host you have not independently checked. を実施。回避策の副作用 (機能低下) を確認した上で。

  3. 6
    Apply patch patch 
    Upgrade guzzlehttp/psr7 to 2.12.3

    ステージング環境で 2.12.3 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と、Step 3 で見つけた異常検知の続報チェックを含めること。

  4. 7
    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 Step 3 と同じログクエリでアラート再発が無いか継続監視。

Affected packages

composer guzzlehttp/psr7
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.12.3"}]}]

References

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