Open Redirect in next (CVE-2026-64645)
Summary
Vulnerability in next (CVE-2026-64645). Risk of unauthorized operations or information disclosure. Exploitable via has. Mitigation: upgrade to 16.2.11 or later.
Original description
The description as published by the source.
Impact
A rewrites() or redirects() rule that builds its external destination hostname from request-controlled input can be pointed at an arbitrary hostname, regardless of the rule's hostname suffix. For a rewrite, Next.js proxies the request to that arbitrary host and serves the response from the application's origin, leading to Server-Side Request forgery. A redirects() rule configured this way is vulnerable to an Open Redirect.
This affects any destination that puts a dynamic segment in the hostname, whether from the path:
// next.config.js
module.exports = {
async rewrites() {
return [
{
source: '/:tenant',
destination: 'https://:tenant.api.example.com',
},
]
},
}
or from a has capture:
// next.config.js
module.exports = {
async rewrites() {
return [
{
source: '/',
has: [{ type: 'query', key: 'region', value: '(?.+)' }],
destination: 'https://:region.api.example.com',
},
]
},
}
Workarounds
If you cannot upgrade immediately, do not build the hostname of an external rewrites() or redirects() destination from user-controlled input. If a dynamic subdomain is required, constrain the value to hostname-safe characters: value: '(?[a-z0-9-]+)'.
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-2026-64645 has been found in next.
Attackers can target a specific entry point like has over the network to misuse the product.
Risk of unauthorized operations or information disclosure. CVSS score: 6.1/10.
What to do: upgrade next to 16.2.11 or later.
If unsure, ask your IT team or search "next CVE-2026-64645" on the vendor's site.
CVE-2026-64645 (next) — CWE-601 / CVSS v3 6.1
Attack vector: remote (network-reachable) / unauthenticated
Attack surface: has
Patched: 16.2.11 — apply immediately
Workaround: If you cannot upgrade immediately, do not build the hostname of an external rewrites() or redirects() destination from user-controlled input.
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-601) exists in next. Attackers reach the vulnerable code path via has without authentication.
Check the vendor advisory for the affected versions of next. Attack surface: has.
Severity: Medium (CVSS 6.1/10). Risk of unauthorized operations or information disclosure.
Update to 16.2.11.
Workaround: If you cannot upgrade immediately, do not build the hostname of an external rewrites() or redirects() destination from user-controlled input.
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
-
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 immediately, do not build the hostname of an external `rewrites()` or `redirects()` destination from user-controlled input.パッチが適用されるまでの応急処置として、If you cannot upgrade immediately, do not build the hostname of an external
rewrites()orredirects()destination from user-controlled input. を実施。回避策の副作用 (機能低下) を確認した上で。 -
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。
-
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。