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CVE-2026-5079
high
CVSS 7.5
Vulnerability in multer (CVE-2026-5079)
Summary
vulnerability in multer (CVE-2026-5079). Risk of unauthorized operations or information disclosure. Exploitable via ``limits.fieldNestingDepth``. Mitigation: upgrade to `3.0.0-alpha.2` or later.
AI summary snake-internal / snake-material-v2
A vulnerability tracked as **CVE-2026-5079** has been found in multer.
Attackers can target a specific entry point like ``limits.fieldNestingDepth`` over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 7.5/10.
What to do: upgrade multer to **3.0.0-alpha.2** or later.
If unsure, ask your IT team or search "multer CVE-2026-5079" on the vendor's site.
CVE-2026-5079 (multer) — CWE-400 / CVSS v3 7.5
Attack vector: remote (network-reachable) / unauthenticated / no user interaction
Attack surface: `limits.fieldNestingDepth` / `limits.fields`
Patched: `3.0.0-alpha.2` — apply immediately
Workaround: Set `limits.fields` to a reasonable value to reduce the number of fields an attacker can send per request.
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-400) exists in multer. Attackers reach the vulnerable code path via ``limits.fieldNestingDepth`` without authentication.
📍 Affected scope
multer — . Attack surface: `limits.fieldNestingDepth` / `limits.fields`.
🔥 Severity
Severity: High (CVSS 7.5/10). Risk of unauthorized operations or information disclosure
🔧 How to fix
Update to **3.0.0-alpha.2**.
🛡️ Workaround
Workaround: Set `limits.fields` to a reasonable value to reduce the number of fields an attacker can send per request.
🔍 Detection
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run `grep -r 'multer' .` 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 'multer' . | 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 `multer` 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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5Apply temporary workaround mitigate
Set `limits.fields` to a reasonable value to reduce the number of fields an attacker can send per request.パッチが適用されるまでの応急処置として、Set `limits.fields` to a reasonable value to reduce the number of fields an attacker can send per request. を実施。回避策の副作用 (機能低下) を確認した上で。
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6Apply patch patch
Upgrade multer to 3.0.0-alpha.2ステージング環境で 3.0.0-alpha.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
npm
multer
[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3.0.0-alpha.2"}]}]