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CVE-2026-55766
medium
CVSS 4.8
Vulnerability in guzzlehttp/psr7 (CVE-2026-55766)
Summary
vulnerability in guzzlehttp/psr7 (CVE-2026-55766). Risk of unauthorized operations or information disclosure. Exploitable via ``Request``. Mitigation: upgrade to `2.12.1` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-55766** has been found in guzzlehttp/psr7.
Attackers can target a specific entry point like ``Request`` over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 4.8/10.
What to do: upgrade guzzlehttp/psr7 to **2.12.1** or later.
If unsure, ask your IT team or search "guzzlehttp/psr7 CVE-2026-55766" on the vendor's site.
CVE-2026-55766 (guzzlehttp/psr7) — CWE-93 / CVSS v3 4.8
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: `Request` / `Response` / `REQUEST_METHOD` / `SERVER_PROTOCOL`
Patched: `2.12.1` — 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-93) exists in guzzlehttp/psr7. Attackers reach the vulnerable code path via ``Request`` without authentication.
📍 Affected scope
guzzlehttp/psr7 — . Attack surface: `Request` / `Response` / `REQUEST_METHOD` / `SERVER_PROTOCOL`.
🔥 Severity
Severity: Medium (CVSS 4.8/10). Risk of unauthorized operations or information disclosure
🔧 How to fix
Update to **2.12.1**.
🛡️ 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 '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
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1Identify 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。
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6Apply patch patch
Upgrade guzzlehttp/psr7 to 2.12.1ステージング環境で 2.12.1 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。
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7Post-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":"2.12.1"}]}]