Vulnerability in next (CVE-2026-64647)
Summary
Vulnerability in next (CVE-2026-64647). Risk of unauthorized operations or information disclosure. Exploitable via fetch. Mitigation: upgrade to 16.2.11 or later.
Original description
The description as published by the source.
Impact
A server-side fetch with a request body may return a cached response body from a different request to the same URL but different body. Confidential data in the POST's response body would then leak to unauthorized requests. Though the request itself will not be deduped.
This is only an issue when receiving request bodies with a content type charset other than UTF-8. For example, the UTF-16 byte sequences for 삃삃 and 섄섄 in the request body would share the same cache.
Workarounds
If you cannot upgrade, consider only making fetch requests with UTF-8 bodies (default in Next.js). Applications using Pages Router are not vulnerable.
Source: GitHub Security Advisories (Global) 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-2026-64647 has been found in next.
Attackers can target a specific entry point like fetch over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 5.4/10.
What to do: upgrade next to 16.2.11 or later.
If unsure, ask your IT team or search "next CVE-2026-64647" on the vendor's site.
CVE-2026-64647 (next) — CWE-116 / CVSS v3 5.4
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: fetch / POST
Patched: 16.2.11 — apply immediately
Workaround: If you cannot upgrade, consider only making fetch requests with UTF-8 bodies (default in Next.js).
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.
A vulnerability (CWE-116) exists in next. Attackers reach the vulnerable code path via fetch without authentication.
Check the vendor advisory for the affected versions of next. Attack surface: fetch / POST.
Severity: Medium (CVSS 5.4/10). Risk of unauthorized operations or information disclosure.
Update to 16.2.11.
Workaround: If you cannot upgrade, consider only making fetch requests with UTF-8 bodies (default in Next.js).
Search webserver/proxy logs for unusual request patterns matching this CVE's known IOCs. Run grep -r 'next' . 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
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1Identify exposure identify
grep -r 'next' . | 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
nextを grep し、稼働しているサービス・バージョンを把握する。 -
2Apply temporary workaround mitigate
If you cannot upgrade, consider only making fetch requests with UTF-8 bodies (default in Next.js).パッチが適用されるまでの応急処置として、If you cannot upgrade, consider only making fetch requests with UTF-8 bodies (default in Next.js). 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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3Apply patch patch
Upgrade next to 16.2.11ステージング環境で 16.2.11 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。
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4Post-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。